In this work,we design and fabricate AlGaN/GaN-based Schottky barrier diodes(SBDs)on a silicon substrate with a trenched n^(+)-GaN cap layer.With the developed physical models,we find that the n^(+)-GaN cap layer prov...In this work,we design and fabricate AlGaN/GaN-based Schottky barrier diodes(SBDs)on a silicon substrate with a trenched n^(+)-GaN cap layer.With the developed physical models,we find that the n^(+)-GaN cap layer provides more electrons into the AlGaN/GaN channel,which is further confirmed experimentally.When compared with the reference device,this increases the two-dimensional electron gas(2DEG)density by two times and leads to a reduced specific ON-resistance(Ron,sp)of~2.4 mΩ·cm^(2).We also adopt the trenched n^(+)-GaN structure such that partial of the n^(+)-GaN is removed by using dry etching process to eliminate the surface electrical conduction when the device is set in the off-state.To suppress the surface defects that are caused by the dry etching process,we also deposit Si_(3)N_(4)layer prior to the deposition of field plate(FP),and we obtain a reduced leakage current of~8×10^(−5)A·cm^(−2)and breakdown voltage(BV)of 876 V.The Baliga’s figure of merit(BFOM)for the proposed structure is increased to~319 MW·cm^(−2).Our investigations also find that the pre-deposited Si_(3)N_(4)layer helps suppress the electron capture and transport processes,which enables the reduced dynamic R_(on,sp).展开更多
This paper studies the exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses by low temperature photoluminescence （PL） measurements. With increasing cap la...This paper studies the exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses by low temperature photoluminescence （PL） measurements. With increasing cap layer thickness, the PL peak energy shifts to lower energy and the coupling strength between the exciton and longitudinal- optical （LO） phonon, described by Huang-Rhys factor, increases remarkably due to an enhancement of the internal electric field. With increasing excitation intensity, the zero-phonon peak shows a blueshift and the Huang-Rhys factor decreases. These results reveal that there is a large built-in electric field in the well layer and the exciton-LO-phonon coupling is strongly affected by the thickness of the cap layer.展开更多
The strain relaxation of an A1GaN barrier layer may be influenced by a thin cap layer above, and affects the transport properties of A1GaN/GaN heterostructures. Compared with the slight strain relaxation found in A1Ga...The strain relaxation of an A1GaN barrier layer may be influenced by a thin cap layer above, and affects the transport properties of A1GaN/GaN heterostructures. Compared with the slight strain relaxation found in A1GaN barrier layer without cap layer, it is found that a thin cap layer can induce considerable changes of strain state in the A1GaN barrier layer. The degree of relaxation of the A1GaN layer significantly influences the transport properties of the two-dimensional electron gas （2DEG） in A1GaN/GaN heterostructures. It is observed that electron mobility decreases with the increasing degree of relaxation of the A1GaN barrier, which is believed to be the main cause of the deterioration of crystalline quality and morphology on the A1GaN/GaN interface. On the other hand, both GaN and A1N cap layers lead to a decrease in 2DEC density. The reduction of 2DEG caused by the GaN cap layer may be attributed to the additional negative polarization charges formed at the interface between CaN and A1GaN, while the reduction of the piezoelectric effect in the A1GaN layer results in the decrease of 2DEC density in the case of A1N cap layer.展开更多
In this study, we investigate the effects of Ga N cap layer thickness on the two-dimensional electron gas（2DEG）electron density and 2DEG electron mobility of Al N/Ga N heterostructures by using the temperature-depen...In this study, we investigate the effects of Ga N cap layer thickness on the two-dimensional electron gas（2DEG）electron density and 2DEG electron mobility of Al N/Ga N heterostructures by using the temperature-dependent Hall measurement and theoretical fitting method. The results of our analysis clearly indicate that the Ga N cap layer thickness of an Al N/Ga N heterostructure has influences on the 2DEG electron density and the electron mobility. For the Al N/Ga N heterostructures with a 3-nm Al N barrier layer, the optimized thickness of the Ga N cap layer is around 4 nm and the strained a-axis lattice constant of the Al N barrier layer is less than that of Ga N.展开更多
The influences of an Fe cap layer on the structural and magnetic properties of FePt/Fe bi-layers are investigated. Compared with single FePt alloy films, a thin Fe layer can affect the crystalline orientation and impr...The influences of an Fe cap layer on the structural and magnetic properties of FePt/Fe bi-layers are investigated. Compared with single FePt alloy films, a thin Fe layer can affect the crystalline orientation and improve the chemical ordering of L10 FePt films. Moreover, the coercivity increases when a thin Fe layer covers the FePt layer. Beyond a critical thickness, however, the Fe cover layer quickens the magnetization reversal of Fe49Pt51/Fe bi-layers by their exchange coupling.展开更多
Infrared-transparent conductors have attracted considerable attention due to their potential applications in electromagnetic shielding,infrared sensors,and photovoltaic devices.However,most known materials face the cr...Infrared-transparent conductors have attracted considerable attention due to their potential applications in electromagnetic shielding,infrared sensors,and photovoltaic devices.However,most known materials face the critical challenge of balancing high infrared transmittance with high electrical conductivity across the broad infrared spectral band(2.5-25μm).While ultra-thin indium tin oxide(ITO)films have been demonstrated to exhibit superior infrared transmittance,their inherent low electrical conductivity necessitates additional enhancement strategies.This study systematically investigates the effects of oxygen vacancy concentration regulation and ultra-thin copper capping layer integration on the infrared optoelectronic properties of 20 nm-thick ITO films.A fundamental trade-off is revealed in ITO films that increased oxygen vacancy content enhances the electrical conductivity while compromising the infrared transmittance.Meanwhile,following the introduction of a Cu capping layer,the Cu/ITO system exhibits opposing dependencies of infrared transmittance and electrical conductivity on the capping layer thickness,with an optimum thickness of~3 nm.Finally,by constructing a Cu(3 nm)/ITO(20 nm)heterostructure with varying oxygen vacancy content,we demonstrate the combined effect of the ultra-thin Cu capping layer and moderate oxygen vacancy content on optimizing the carrier transport network.This configuration simultaneously minimizes surface/interfacial reflection and absorption losses,achieving high infrared transmittance(0.861)and a low sheet resistance of 400 W/sq.Our findings highlight the critical role of the combined effect of metal/oxide heterostructure design and defect engineering in optimizing infrared-transparent conductive properties.展开更多
Bioreactive thin-layer capping（BTC）with biozeolite provides a potential remediation design that can sustainably treat N contamination from sediment and overlying water in eutrophic water bodies.Nitrogen（N）reductio...Bioreactive thin-layer capping（BTC）with biozeolite provides a potential remediation design that can sustainably treat N contamination from sediment and overlying water in eutrophic water bodies.Nitrogen（N）reduction using BTC with biozeolite was examined in a field incubation experiment in a eutrophic river in Yangzhou,Jiangsu Province,China.The biozeolite was zeolite with attached bacteria,including two isolated heterotrophic nitrifiers（Bacillus spp.）and two isolated aerobic denitrifiers（Acinetobacter spp.）.The results showed that the total nitrogen（TN）reduction efficiency of the overlying water by BTC with biozeolite（with thickness of about 2 mm）reached a maximum（56.69%）at day 34,and simultaneous heterotrophic nitrification and aerobic denitrification occurred in the BTC system until day 34.There was a significant difference in the TN concentrations of the overlying water between biozeolite capping and control（t-test;p〈0.05）.The biozeolite had very strong in situ bioregeneration ability.Carbon was the main source of nitrifier growth.However,both dissolved oxygen（DO）and carbon concentrations affected denitrifier growth.In particular,DO concentrations greater than 3 mg/L inhibited denitrifier growth.Therefore,BTC with biozeolite was found to be a feasible technique to reduce N in a eutrophic river.However,it is necessary to further strengthen the adaptability of aerobic denitrifiers through changing domestication methods or conditions.展开更多
The thickness effect of the TiN capping layer on the time dependent dielectric breakdown（TDDB） characteristic of ultra-thin EOT high-k metal gate NMOSFET is investigated in this paper.Based on experimental results,i...The thickness effect of the TiN capping layer on the time dependent dielectric breakdown（TDDB） characteristic of ultra-thin EOT high-k metal gate NMOSFET is investigated in this paper.Based on experimental results,it is found that the device with a thicker TiN layer has a more promising reliability characteristic than that with a thinner TiN layer.From the charge pumping measurement and secondary ion mass spectroscopy（SIMS） analysis,it is indicated that the sample with the thicker TiN layer introduces more Cl passivation at the IL/Si interface and exhibits a lower interface trap density.In addition,the influences of interface and bulk trap density ratio Nit/Not are studied by TDDB simulations through combining percolation theory and the kinetic Monte Carlo（kMC） method.The lifetime reduction and Weibull slope lowering are explained by interface trap effects for TiN capping layers with different thicknesses.展开更多
The rutile TiO2 nanorod arrays with 240 nm in length, 30 nm in diameter, and 420 btm 2 in areal density were prepared by the hydrothermal method to replace the typical 200-300 nm thick mesoporous TiO2 thin films in pe...The rutile TiO2 nanorod arrays with 240 nm in length, 30 nm in diameter, and 420 btm 2 in areal density were prepared by the hydrothermal method to replace the typical 200-300 nm thick mesoporous TiO2 thin films in perovskite solar cells. The CH3NH3PbI3 xBrx capping layers with different thicknesses were obtained on the TiO2 nanorod arrays using different concentration PbI2.DMSO complex precursor solutions in DMF and the photovoltaic performances of the corresponding solar cells were compared. The perovskite solar cells based on 240 nm long TiO2 nanorod arrays and 420 nm thick CH3NH3PbI3 xBrx capping layers showed the best photoelectric conversion efficiency （PCE） of 15.56% and the average PCE of 14.93 ± 0.63% at the relative humidity of 50%-54% under the illumination of simulated AM 1.5 sunlight （100 mW.cm-2）.展开更多
It has been noted that when the convective Richardson number Ri* is used to characterize the depth of the entrainment zone, various parameterization schemes can be obtained. This situation is often attributed to the i...It has been noted that when the convective Richardson number Ri* is used to characterize the depth of the entrainment zone, various parameterization schemes can be obtained. This situation is often attributed to the invalidity of parcel theory. However, evidence shows that the convective Richardson number Ri* might be an improper characteristic scaling parameter for the entrainment process. An attempt to use an innovative parameter to parameterize the entrainment-zone thickness has been made in this paper. Based on the examination of the data of water-tank experiments and atmospheric measurements, it is found that the total lapse rate of potential temperature across the entrainment zone is proportional to that of the capping inversion layer. Inserting this relationship into the so-called parcel theory, it thus gives a new parameterization scheme for the depth of the entrainment zone. This scheme includes the lapse rate of the capping inversion layer that plays an important role in the entrainment process. Its physical representation is reasonable. The new scheme gives a better ordering of the data measured in both water-tank and atmosphere as compared with the traditional method using Ri*. These indicate that the parcel theory can describe the entrainment process suitably and that the new parameter is better than Ri*.展开更多
Based on detailed measurements of density and a numerous data on temperature in shallow boreholes (about 20m deep), the thermal properties and temperature distribution of snow / firn layer on the Law Dome ice cap, Ant...Based on detailed measurements of density and a numerous data on temperature in shallow boreholes (about 20m deep), the thermal properties and temperature distribution of snow / firn layer on the Law Dome ice cap, Antarctica, are discussed. According to a review of works on thermal properties of snow by Yen (1981), a relationship between thermal conductivity (K) and density (ρ) is proposed to be expressed by a formula, K=0.0784+2.697/ρ2. Then an eqation of heat transfer in a deformed ununiform medium is applied and solved analytically by two approaches. Comparison of calculated and measured temperatures indicates that the difference is mainly dependent on the determination of boundary donditions.展开更多
Developing a bridge capping layer between perovskite and hole transport layer materials(HTMs)in the n-i-p perovskite solar cells(pero-SCs)is an effective approach to modify the morphology of HTMs and passivate the per...Developing a bridge capping layer between perovskite and hole transport layer materials(HTMs)in the n-i-p perovskite solar cells(pero-SCs)is an effective approach to modify the morphology of HTMs and passivate the perovskite simultaneously.Herein,we select the quinoxaline-based bifunctional passivation agent,quinoxalin-6-yl-methylamine hydrochloride(Qx MACl),as the bridging layer,and a D-A copolymer PBQ12 containing the same quinoxaline unit as an HTM for the n-i-p pero-SCs.Due to theπ-πstacking among the common quinoxaline units in the bridge layer and HTM,Qx MACl induces theπ-πstacking of the PBQ12 film and improves the film morphology of HTMs with better conductivity.Additionally,Qx MACl can effectively passivate the perovskite surface,and PBQ12 possesses appropriate energy levels and high hole mobility.The pero-SCs based on FAPbI_(3)with PBQ12/Qx MACl treatment showed a higher power conversion efficiency(PCE)of 24.05%and outstanding stability,maintaining 95.4%and 92.1%of its initial PCE after 750 h of storage and after over 800 h of thermal annealing at 85℃,respectively.To further enhance the PCE of the PBQ12/Qx MACl-based devices,we developed a non-metal ion dopant for the PBQ12 HTM.Through trace doping of PBQ12 HTM by the non-metal ion dopant,the PCE of the PBQ12/Qx MACl-based devices reached 25.24%(the calibrated PCE of 24.55%by the National Institute of Metrology,China).展开更多
基金supported by National Natural Science Foundation of China under grant U23A20361Key Area R&D Program of Guangdong Province under grant 2022B0701180001.
文摘In this work,we design and fabricate AlGaN/GaN-based Schottky barrier diodes(SBDs)on a silicon substrate with a trenched n^(+)-GaN cap layer.With the developed physical models,we find that the n^(+)-GaN cap layer provides more electrons into the AlGaN/GaN channel,which is further confirmed experimentally.When compared with the reference device,this increases the two-dimensional electron gas(2DEG)density by two times and leads to a reduced specific ON-resistance(Ron,sp)of~2.4 mΩ·cm^(2).We also adopt the trenched n^(+)-GaN structure such that partial of the n^(+)-GaN is removed by using dry etching process to eliminate the surface electrical conduction when the device is set in the off-state.To suppress the surface defects that are caused by the dry etching process,we also deposit Si_(3)N_(4)layer prior to the deposition of field plate(FP),and we obtain a reduced leakage current of~8×10^(−5)A·cm^(−2)and breakdown voltage(BV)of 876 V.The Baliga’s figure of merit(BFOM)for the proposed structure is increased to~319 MW·cm^(−2).Our investigations also find that the pre-deposited Si_(3)N_(4)layer helps suppress the electron capture and transport processes,which enables the reduced dynamic R_(on,sp).
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60876007 and 10974165)the Research Program of Xiamen Municipal Science and Technology Bureau,China (Grant No. 2006AA03Z110)
文摘This paper studies the exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses by low temperature photoluminescence （PL） measurements. With increasing cap layer thickness, the PL peak energy shifts to lower energy and the coupling strength between the exciton and longitudinal- optical （LO） phonon, described by Huang-Rhys factor, increases remarkably due to an enhancement of the internal electric field. With increasing excitation intensity, the zero-phonon peak shows a blueshift and the Huang-Rhys factor decreases. These results reveal that there is a large built-in electric field in the well layer and the exciton-LO-phonon coupling is strongly affected by the thickness of the cap layer.
基金Project supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China (Grant No.2008ZX01002-002)the Major Program and the Key Program of National Natural Science Foundation of China (Grant Nos.60890191 and 60736033)
文摘The strain relaxation of an A1GaN barrier layer may be influenced by a thin cap layer above, and affects the transport properties of A1GaN/GaN heterostructures. Compared with the slight strain relaxation found in A1GaN barrier layer without cap layer, it is found that a thin cap layer can induce considerable changes of strain state in the A1GaN barrier layer. The degree of relaxation of the A1GaN layer significantly influences the transport properties of the two-dimensional electron gas （2DEG） in A1GaN/GaN heterostructures. It is observed that electron mobility decreases with the increasing degree of relaxation of the A1GaN barrier, which is believed to be the main cause of the deterioration of crystalline quality and morphology on the A1GaN/GaN interface. On the other hand, both GaN and A1N cap layers lead to a decrease in 2DEC density. The reduction of 2DEG caused by the GaN cap layer may be attributed to the additional negative polarization charges formed at the interface between CaN and A1GaN, while the reduction of the piezoelectric effect in the A1GaN layer results in the decrease of 2DEC density in the case of A1N cap layer.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11174182 and 61306113)the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20110131110005)
文摘In this study, we investigate the effects of Ga N cap layer thickness on the two-dimensional electron gas（2DEG）electron density and 2DEG electron mobility of Al N/Ga N heterostructures by using the temperature-dependent Hall measurement and theoretical fitting method. The results of our analysis clearly indicate that the Ga N cap layer thickness of an Al N/Ga N heterostructure has influences on the 2DEG electron density and the electron mobility. For the Al N/Ga N heterostructures with a 3-nm Al N barrier layer, the optimized thickness of the Ga N cap layer is around 4 nm and the strained a-axis lattice constant of the Al N barrier layer is less than that of Ga N.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 60490290,60678008 and 50771032)the National Basic Research Program of China (Grant No 2009CB929201)the Science Foundation of the Science and Technology Committee of Shanghai (Grant No 06DJ14007)
文摘The influences of an Fe cap layer on the structural and magnetic properties of FePt/Fe bi-layers are investigated. Compared with single FePt alloy films, a thin Fe layer can affect the crystalline orientation and improve the chemical ordering of L10 FePt films. Moreover, the coercivity increases when a thin Fe layer covers the FePt layer. Beyond a critical thickness, however, the Fe cover layer quickens the magnetization reversal of Fe49Pt51/Fe bi-layers by their exchange coupling.
基金supported by the National Key R&D Program of China(Grant No.2022YFB3806300).
文摘Infrared-transparent conductors have attracted considerable attention due to their potential applications in electromagnetic shielding,infrared sensors,and photovoltaic devices.However,most known materials face the critical challenge of balancing high infrared transmittance with high electrical conductivity across the broad infrared spectral band(2.5-25μm).While ultra-thin indium tin oxide(ITO)films have been demonstrated to exhibit superior infrared transmittance,their inherent low electrical conductivity necessitates additional enhancement strategies.This study systematically investigates the effects of oxygen vacancy concentration regulation and ultra-thin copper capping layer integration on the infrared optoelectronic properties of 20 nm-thick ITO films.A fundamental trade-off is revealed in ITO films that increased oxygen vacancy content enhances the electrical conductivity while compromising the infrared transmittance.Meanwhile,following the introduction of a Cu capping layer,the Cu/ITO system exhibits opposing dependencies of infrared transmittance and electrical conductivity on the capping layer thickness,with an optimum thickness of~3 nm.Finally,by constructing a Cu(3 nm)/ITO(20 nm)heterostructure with varying oxygen vacancy content,we demonstrate the combined effect of the ultra-thin Cu capping layer and moderate oxygen vacancy content on optimizing the carrier transport network.This configuration simultaneously minimizes surface/interfacial reflection and absorption losses,achieving high infrared transmittance(0.861)and a low sheet resistance of 400 W/sq.Our findings highlight the critical role of the combined effect of metal/oxide heterostructure design and defect engineering in optimizing infrared-transparent conductive properties.
基金supported by the National Science and Technology Pillar Program(No.2012BAC04B02)the National Natural Science Fund of China(No.51408243)+3 种基金the Natural Science Foundation of Fujian Province of China(No.2015J01213)the Fundamental Research Funds for Central Universities(No.11QZR07)the Science and Technology Plan Fund of Quanzhou City(No.2014Z218)the Research Funds of Huaqiao University(No.14BS216)
文摘Bioreactive thin-layer capping（BTC）with biozeolite provides a potential remediation design that can sustainably treat N contamination from sediment and overlying water in eutrophic water bodies.Nitrogen（N）reduction using BTC with biozeolite was examined in a field incubation experiment in a eutrophic river in Yangzhou,Jiangsu Province,China.The biozeolite was zeolite with attached bacteria,including two isolated heterotrophic nitrifiers（Bacillus spp.）and two isolated aerobic denitrifiers（Acinetobacter spp.）.The results showed that the total nitrogen（TN）reduction efficiency of the overlying water by BTC with biozeolite（with thickness of about 2 mm）reached a maximum（56.69%）at day 34,and simultaneous heterotrophic nitrification and aerobic denitrification occurred in the BTC system until day 34.There was a significant difference in the TN concentrations of the overlying water between biozeolite capping and control（t-test;p〈0.05）.The biozeolite had very strong in situ bioregeneration ability.Carbon was the main source of nitrifier growth.However,both dissolved oxygen（DO）and carbon concentrations affected denitrifier growth.In particular,DO concentrations greater than 3 mg/L inhibited denitrifier growth.Therefore,BTC with biozeolite was found to be a feasible technique to reduce N in a eutrophic river.However,it is necessary to further strengthen the adaptability of aerobic denitrifiers through changing domestication methods or conditions.
基金supported by the National High Technology Research and Development Program of China(Grant No.SS2015AA010601)the National Natural Science Foundation of China(Grant Nos.61176091 and 61306129)the Opening Project of Key Laboratory of Microelectronics Devices&Integrated Technology,Institute of Micro Electronics of Chinese Academy of Sciences
文摘The thickness effect of the TiN capping layer on the time dependent dielectric breakdown（TDDB） characteristic of ultra-thin EOT high-k metal gate NMOSFET is investigated in this paper.Based on experimental results,it is found that the device with a thicker TiN layer has a more promising reliability characteristic than that with a thinner TiN layer.From the charge pumping measurement and secondary ion mass spectroscopy（SIMS） analysis,it is indicated that the sample with the thicker TiN layer introduces more Cl passivation at the IL/Si interface and exhibits a lower interface trap density.In addition,the influences of interface and bulk trap density ratio Nit/Not are studied by TDDB simulations through combining percolation theory and the kinetic Monte Carlo（kMC） method.The lifetime reduction and Weibull slope lowering are explained by interface trap effects for TiN capping layers with different thicknesses.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51472071 and 51272061)Talent Project of Hefei University of Technology,China(Grant Nos.75010-037004 and 75010-037003)
文摘The rutile TiO2 nanorod arrays with 240 nm in length, 30 nm in diameter, and 420 btm 2 in areal density were prepared by the hydrothermal method to replace the typical 200-300 nm thick mesoporous TiO2 thin films in perovskite solar cells. The CH3NH3PbI3 xBrx capping layers with different thicknesses were obtained on the TiO2 nanorod arrays using different concentration PbI2.DMSO complex precursor solutions in DMF and the photovoltaic performances of the corresponding solar cells were compared. The perovskite solar cells based on 240 nm long TiO2 nanorod arrays and 420 nm thick CH3NH3PbI3 xBrx capping layers showed the best photoelectric conversion efficiency （PCE） of 15.56% and the average PCE of 14.93 ± 0.63% at the relative humidity of 50%-54% under the illumination of simulated AM 1.5 sunlight （100 mW.cm-2）.
基金This paper was supported by the National Natural Science Foundation of China under Grant Nos.40105002 and 40333027.
文摘It has been noted that when the convective Richardson number Ri* is used to characterize the depth of the entrainment zone, various parameterization schemes can be obtained. This situation is often attributed to the invalidity of parcel theory. However, evidence shows that the convective Richardson number Ri* might be an improper characteristic scaling parameter for the entrainment process. An attempt to use an innovative parameter to parameterize the entrainment-zone thickness has been made in this paper. Based on the examination of the data of water-tank experiments and atmospheric measurements, it is found that the total lapse rate of potential temperature across the entrainment zone is proportional to that of the capping inversion layer. Inserting this relationship into the so-called parcel theory, it thus gives a new parameterization scheme for the depth of the entrainment zone. This scheme includes the lapse rate of the capping inversion layer that plays an important role in the entrainment process. Its physical representation is reasonable. The new scheme gives a better ordering of the data measured in both water-tank and atmosphere as compared with the traditional method using Ri*. These indicate that the parcel theory can describe the entrainment process suitably and that the new parameter is better than Ri*.
文摘Based on detailed measurements of density and a numerous data on temperature in shallow boreholes (about 20m deep), the thermal properties and temperature distribution of snow / firn layer on the Law Dome ice cap, Antarctica, are discussed. According to a review of works on thermal properties of snow by Yen (1981), a relationship between thermal conductivity (K) and density (ρ) is proposed to be expressed by a formula, K=0.0784+2.697/ρ2. Then an eqation of heat transfer in a deformed ununiform medium is applied and solved analytically by two approaches. Comparison of calculated and measured temperatures indicates that the difference is mainly dependent on the determination of boundary donditions.
基金supported by the National Key Research and Development Program of China(2019YFA0705900)the National Natural Science Foundation of China(52103243,61904181,52173188)+1 种基金the Key Research Program of the Chinese Academy of Sciences(XDPB13)the Basic and Applied Basic Research Major Program of Guangdong Province(2019B030302007)。
文摘Developing a bridge capping layer between perovskite and hole transport layer materials(HTMs)in the n-i-p perovskite solar cells(pero-SCs)is an effective approach to modify the morphology of HTMs and passivate the perovskite simultaneously.Herein,we select the quinoxaline-based bifunctional passivation agent,quinoxalin-6-yl-methylamine hydrochloride(Qx MACl),as the bridging layer,and a D-A copolymer PBQ12 containing the same quinoxaline unit as an HTM for the n-i-p pero-SCs.Due to theπ-πstacking among the common quinoxaline units in the bridge layer and HTM,Qx MACl induces theπ-πstacking of the PBQ12 film and improves the film morphology of HTMs with better conductivity.Additionally,Qx MACl can effectively passivate the perovskite surface,and PBQ12 possesses appropriate energy levels and high hole mobility.The pero-SCs based on FAPbI_(3)with PBQ12/Qx MACl treatment showed a higher power conversion efficiency(PCE)of 24.05%and outstanding stability,maintaining 95.4%and 92.1%of its initial PCE after 750 h of storage and after over 800 h of thermal annealing at 85℃,respectively.To further enhance the PCE of the PBQ12/Qx MACl-based devices,we developed a non-metal ion dopant for the PBQ12 HTM.Through trace doping of PBQ12 HTM by the non-metal ion dopant,the PCE of the PBQ12/Qx MACl-based devices reached 25.24%(the calibrated PCE of 24.55%by the National Institute of Metrology,China).
