Indium selenide(InSe),as a wide-bandgap semiconductor,has received extensive attention in the flexible electronics field in recent years due to its exceptional plasticity and promising thermoelectric performance.Howev...Indium selenide(InSe),as a wide-bandgap semiconductor,has received extensive attention in the flexible electronics field in recent years due to its exceptional plasticity and promising thermoelectric performance.However,the low carrier concentration severely limits its thermoelectric performance improvement.In this work,we conducted contrasting strategies that can be employed to increase the carrier concentration of InSe,including bandgap narrowing and heterovalent doping.Specifically,the carrier concentration initially increases as a result of the reduced bandgap upon Te alloying and then slightly decreases due to the weak electronegativity of Te.Whereas Br doping realizes high carrier concentration by pushing the Fermi level into the conduction bands and activating the multiple bands.On the other hand,both Te and Br obviously suppress the thermal conductivity due to the point defect scattering.By contrast,Br doping realizes a higher thermoelectric performance with a maximum ZT of~0.13 at 773 K benefiting from the better optimization of carrier concentration.This work elucidates the strategies for enhancing carrier concentration at anion sites and demonstrates the high efficiency of halogen doping in InSe.Moreover,the carrier concentration of InSe is promising to be further optimized,and future work should focus on employing approaches such as cation doping or secondphase compositing.展开更多
InSe has emerged as a promising candidate for next-generation electronics due to its predicted ultrahigh electrical performance.However,the efficacy of the InSe transistor in meeting application requirements is hinder...InSe has emerged as a promising candidate for next-generation electronics due to its predicted ultrahigh electrical performance.However,the efficacy of the InSe transistor in meeting application requirements is hindered due to its sensitivity to interfaces.In this study,we have achieved notable enhancement in the electrical performance of InSe transistors through interface engineering.We engineered an InSe/h-BN heterostructure,effectively suppressing dielectric layer-induced scattering.Additionally,we successfully established excellent metal-semiconductor contacts using graphene ribbons as a buffer layer.Through a methodical approach to interface engineering,our graphene/InSe/h-BN transistor demonstrates impressive on-state current,field-effect mobility,and on/off ratio at room temperature,reaching values as high as 1.1 mA/μm,904 cm^(2)·V^(-1)·s^(-1),and>10~6,respectively.Theoretical computations corroborate that the graphene/InSe heterostructure shows significant interlayer charge transfer and weak interlayer interaction,contributing to the enhanced performance of InSe transistors.This research offers a comprehensive strategy to elevate the electrical performance of InSe transistors,paving the way for their utilization in future electronic applications.展开更多
As a fundamental surface property of two-dimensional(2 D)materials,surface potential is critical for their emerging electronic applications and essential for van der Waals heterostructure engineering.Here,we report th...As a fundamental surface property of two-dimensional(2 D)materials,surface potential is critical for their emerging electronic applications and essential for van der Waals heterostructure engineering.Here,we report the surface potential of few-layer InSe.The effect of layer count,light intensity and different deposited substrates is considered.Few-layer InSe flakes were exfoliated from bulk InSe crystals on Si/SiO_(2)with 300-nm-thick thermal oxide and Si/SiO_(2)with 300-nm-thick thermal oxide and prefabricated micro-wells with 3μm in diameter.The samples were measured by Kelvin probe force microscopy and tuned by an integrated 405-nm(3.06 eV)laser.Based on the work function of SiO_(2)(5.00 eV),the work functions of supported and suspended InSe are determined.These results show that the work function of InSe decreases with the increase in the layer count of both supported InSe and suspended InSe.Besides,by introducing a tunable laser light,the influence of light intensity on surface potential of supported InSe was studied.The surface potential(SP)and surface potential shift between light and dark states(ASP=SP_(lignt)-SP_(dark))of supported InSe were measured and determined.These results present that the surface potential of supported InSe decreases with the increase in the light intensity and also decreases with the increase in the layer count.This is evident that light excites electrons,resulting in decreased surface potential,and the amount of electrons excited is correlated with light intensity.Meanwhile,⊿SP between light and dark states decreases with the increase in the layer count,which suggests that the influence of light illumination decreases with the increase in the layer count of few-layer InSe flakes.展开更多
Recently, two dimensional In Se attracts great attentions as potential hydrogen production photocatalysts.Here, comprehensive investigations on the hydrogen evolution reaction activity of In Se monolayer with3 d trans...Recently, two dimensional In Se attracts great attentions as potential hydrogen production photocatalysts.Here, comprehensive investigations on the hydrogen evolution reaction activity of In Se monolayer with3 d transition metal doping and biaxial strain were performed based on the density functional theory.Transition metal dopants significantly increase the bonding strength between H and Se, and then adjust the hydrogen adsorption free energy to 0.02 e V by Zn doping. The enhanced hydrogen evolution reaction activity results from less electron occupying H 1 s-Se 4 pzanti-bonding states, which is well correlated with the pzband center level. Importantly, the universal scalling law was proposed to descript the evolution of hydrogen adsorption free energy including both doping and strain effects. Moreover, with appropriate band alignment, optical absorption, and carriers separation ability, Zn doped In Se monolayer is considered as a promising candidate of visible-light photocatalyst for hydrogen production.展开更多
Two-dimensional(2D)InSe and WS_(2)exhibit promising characteristics for optoelectronic applications.However,they both have poor absorption of visible light due to wide bandgaps:2D InSe has high electron mobility but l...Two-dimensional(2D)InSe and WS_(2)exhibit promising characteristics for optoelectronic applications.However,they both have poor absorption of visible light due to wide bandgaps:2D InSe has high electron mobility but low hole mobility,while 2D WS_(2)is on the contrary.We propose a 2D heterostructure composed of their monolayers as a solution to both problems.Our first-principles calculations show that the heterostructure has a type-Ⅱband alignment as expected.Consequently,the bandgap of the heterostructure is reduced to 2.19 eV,which is much smaller than those of the monolayers.The reduction in bandgap leads to a considerable enhancement of the visible-light absorption,such as about fivefold(threefold)increase in comparison to monolayer InSe(WS_(2))at the wavelength of 490 nm.Meanwhile,the type-Ⅱband alignment also facilitates the spatial separation of photogenerated electron-hole pairs;i.e.,electrons(holes)reside preferably in the InSe(WS_(2))layer.As a result,the two layers complement each other in carrier mobilities of the heterostructure:the photogenerated electrons and holes inherit the large mobilities from the InSe and WS_(2)monolayers,respectively.展开更多
We report the electrical transport properties of InSe flakes electrostatically gated by a solid ion conductor.The large tuning capability of the solid ion conductor as gating dielectric is confirmed by the saturation ...We report the electrical transport properties of InSe flakes electrostatically gated by a solid ion conductor.The large tuning capability of the solid ion conductor as gating dielectric is confirmed by the saturation gate voltage as low as^1 V and steep subthreshold swing(83 mV/dec).The p-type conduction behavior of InSe is obtained when negative gate voltages are biased.Chemical doping of the solid ion conductor is suppressed by inserting a buffer layer of hexagonal boron nitride(h-BN)between InSe and the solid-ion-conductor substrate.By comparing the performance of devices with and without h-BN,the capacitance of solid ion conductors is extracted to be the same as that of^2 nm h-BN,and the mobility of InSe on solid ion conductors is comparable to that on the SiO2 substrate.Our results show that solid ion conductors provide a facile and powerful method for electrostatic doping.展开更多
Interlayer coupling in layered semiconductors can significantly affect their optoelectronic properties.However,understanding the mechanisms behind the interlayer coupling at the atomic level is not straightforward.Her...Interlayer coupling in layered semiconductors can significantly affect their optoelectronic properties.However,understanding the mechanisms behind the interlayer coupling at the atomic level is not straightforward.Here,we study modulations of the electronic structure induced by the interlayer coupling in theγ-phase of indium selenide(γ-InSe)using scanning probe techniques.We observe a strong dependence of the energy gap on the sample thickness and a small effective mass along the stacking direction,which are attributed to strong interlayer coupling.In addition,the moirépatterns observed inγ-InSe display a small band-gap variation and nearly constant local differential conductivity along the patterns.This suggests that modulation of the electronic structure induced by the moirépotential is smeared out,indicating the presence of a significant interlayer coupling.Our theoretical calculations confirm that the interlayer coupling inγ-InSe is not only of the van der Waals origin,but also exhibits some degree of hybridization between the layers.Strong interlayer coupling might play an important role in the performance ofγ-InSe-based devices.展开更多
基金National Natural Science Foundation of China(52272006,52371193,52001231)Shanghai Academic/Technology Research Leader(23XD1421200)+3 种基金Oriental Scholars of Shanghai Universities(TP2022122)Space Application System of China Manned Space Program,Shanghai Rising-star Program(23QA1403900)Chenguang Program supported by Shanghai Education Development Foundation&Shanghai Municipal Education CommissionOpen Research Fund of Key Laboratory of Polar Materials and Devices,Ministry of Education。
基金supported by the National Science Fund for Distinguished Young Scholars(No.51925101)the Tencent Xplorer Prize,the National Natural Science Foundation of China(Nos.52371208,52250090,52002042,51772012,51571007and 12374023)+1 种基金Beijing Municipal Natural Science Foundation(JQ18004)the 111 Project(B17002)。
文摘Indium selenide(InSe),as a wide-bandgap semiconductor,has received extensive attention in the flexible electronics field in recent years due to its exceptional plasticity and promising thermoelectric performance.However,the low carrier concentration severely limits its thermoelectric performance improvement.In this work,we conducted contrasting strategies that can be employed to increase the carrier concentration of InSe,including bandgap narrowing and heterovalent doping.Specifically,the carrier concentration initially increases as a result of the reduced bandgap upon Te alloying and then slightly decreases due to the weak electronegativity of Te.Whereas Br doping realizes high carrier concentration by pushing the Fermi level into the conduction bands and activating the multiple bands.On the other hand,both Te and Br obviously suppress the thermal conductivity due to the point defect scattering.By contrast,Br doping realizes a higher thermoelectric performance with a maximum ZT of~0.13 at 773 K benefiting from the better optimization of carrier concentration.This work elucidates the strategies for enhancing carrier concentration at anion sites and demonstrates the high efficiency of halogen doping in InSe.Moreover,the carrier concentration of InSe is promising to be further optimized,and future work should focus on employing approaches such as cation doping or secondphase compositing.
基金the support of the National Natural Science Foundation of China (Grant No.62204030)supported in part by the National Natural Science Foundation of China (Grant Nos.62122036,62034004,61921005,61974176,and 12074176)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDB44000000)。
文摘InSe has emerged as a promising candidate for next-generation electronics due to its predicted ultrahigh electrical performance.However,the efficacy of the InSe transistor in meeting application requirements is hindered due to its sensitivity to interfaces.In this study,we have achieved notable enhancement in the electrical performance of InSe transistors through interface engineering.We engineered an InSe/h-BN heterostructure,effectively suppressing dielectric layer-induced scattering.Additionally,we successfully established excellent metal-semiconductor contacts using graphene ribbons as a buffer layer.Through a methodical approach to interface engineering,our graphene/InSe/h-BN transistor demonstrates impressive on-state current,field-effect mobility,and on/off ratio at room temperature,reaching values as high as 1.1 mA/μm,904 cm^(2)·V^(-1)·s^(-1),and>10~6,respectively.Theoretical computations corroborate that the graphene/InSe heterostructure shows significant interlayer charge transfer and weak interlayer interaction,contributing to the enhanced performance of InSe transistors.This research offers a comprehensive strategy to elevate the electrical performance of InSe transistors,paving the way for their utilization in future electronic applications.
基金the Key-Area Research and Development Program of Guangdong Province(No.2018B010109009)the Shenzhen Science and Technology Innovation Committee(Nos.JCYJ20170818155752559 and JCYJ20170818160815002)+3 种基金the Instrument Developing Project of Chinese Academy of Sciences(No.ZDKYYQ20180004)the National Natural Science Foundation of China(No.11872203)the National Natural Science Foundation of China for Creative Research Groups(No.51921003)support of the China Scholarship Council。
文摘As a fundamental surface property of two-dimensional(2 D)materials,surface potential is critical for their emerging electronic applications and essential for van der Waals heterostructure engineering.Here,we report the surface potential of few-layer InSe.The effect of layer count,light intensity and different deposited substrates is considered.Few-layer InSe flakes were exfoliated from bulk InSe crystals on Si/SiO_(2)with 300-nm-thick thermal oxide and Si/SiO_(2)with 300-nm-thick thermal oxide and prefabricated micro-wells with 3μm in diameter.The samples were measured by Kelvin probe force microscopy and tuned by an integrated 405-nm(3.06 eV)laser.Based on the work function of SiO_(2)(5.00 eV),the work functions of supported and suspended InSe are determined.These results show that the work function of InSe decreases with the increase in the layer count of both supported InSe and suspended InSe.Besides,by introducing a tunable laser light,the influence of light intensity on surface potential of supported InSe was studied.The surface potential(SP)and surface potential shift between light and dark states(ASP=SP_(lignt)-SP_(dark))of supported InSe were measured and determined.These results present that the surface potential of supported InSe decreases with the increase in the light intensity and also decreases with the increase in the layer count.This is evident that light excites electrons,resulting in decreased surface potential,and the amount of electrons excited is correlated with light intensity.Meanwhile,⊿SP between light and dark states decreases with the increase in the layer count,which suggests that the influence of light illumination decreases with the increase in the layer count of few-layer InSe flakes.
基金supported by the National Natural Science Foundation of China(11804023)the Natural Science Foundation of Tianjin(18JCQNJC02700)。
文摘Recently, two dimensional In Se attracts great attentions as potential hydrogen production photocatalysts.Here, comprehensive investigations on the hydrogen evolution reaction activity of In Se monolayer with3 d transition metal doping and biaxial strain were performed based on the density functional theory.Transition metal dopants significantly increase the bonding strength between H and Se, and then adjust the hydrogen adsorption free energy to 0.02 e V by Zn doping. The enhanced hydrogen evolution reaction activity results from less electron occupying H 1 s-Se 4 pzanti-bonding states, which is well correlated with the pzband center level. Importantly, the universal scalling law was proposed to descript the evolution of hydrogen adsorption free energy including both doping and strain effects. Moreover, with appropriate band alignment, optical absorption, and carriers separation ability, Zn doped In Se monolayer is considered as a promising candidate of visible-light photocatalyst for hydrogen production.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11404013,11474012,11364030,61622406,61571415,51502283 and 11605003the National Key Research and Development Program of China under Grant No2017YFA0206303the MOST of China,and the 2018 Graduate Research Program of Beijing Technology and Business University
文摘Two-dimensional(2D)InSe and WS_(2)exhibit promising characteristics for optoelectronic applications.However,they both have poor absorption of visible light due to wide bandgaps:2D InSe has high electron mobility but low hole mobility,while 2D WS_(2)is on the contrary.We propose a 2D heterostructure composed of their monolayers as a solution to both problems.Our first-principles calculations show that the heterostructure has a type-Ⅱband alignment as expected.Consequently,the bandgap of the heterostructure is reduced to 2.19 eV,which is much smaller than those of the monolayers.The reduction in bandgap leads to a considerable enhancement of the visible-light absorption,such as about fivefold(threefold)increase in comparison to monolayer InSe(WS_(2))at the wavelength of 490 nm.Meanwhile,the type-Ⅱband alignment also facilitates the spatial separation of photogenerated electron-hole pairs;i.e.,electrons(holes)reside preferably in the InSe(WS_(2))layer.As a result,the two layers complement each other in carrier mobilities of the heterostructure:the photogenerated electrons and holes inherit the large mobilities from the InSe and WS_(2)monolayers,respectively.
基金Project supported by the National Key Research and Development Projects of China(Grant Nos.2016YFA0202300 and 2018FYA0305800)the National Natural Science Foundation of China(Grant Nos.61674170 and 61888102)+1 种基金the K.C.Wong Education Foundation,the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDB30000000 and XDB28000000)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.Y201902).
文摘We report the electrical transport properties of InSe flakes electrostatically gated by a solid ion conductor.The large tuning capability of the solid ion conductor as gating dielectric is confirmed by the saturation gate voltage as low as^1 V and steep subthreshold swing(83 mV/dec).The p-type conduction behavior of InSe is obtained when negative gate voltages are biased.Chemical doping of the solid ion conductor is suppressed by inserting a buffer layer of hexagonal boron nitride(h-BN)between InSe and the solid-ion-conductor substrate.By comparing the performance of devices with and without h-BN,the capacitance of solid ion conductors is extracted to be the same as that of^2 nm h-BN,and the mobility of InSe on solid ion conductors is comparable to that on the SiO2 substrate.Our results show that solid ion conductors provide a facile and powerful method for electrostatic doping.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51772087,11804089,11574350,11904094,and 51972106)the Natural Science Foundation of Hunan Province,China(Grant Nos.2018JJ3025,2019JJ50034,and 2019JJ50073)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB30000000)the Fundamental Research Funds for the Central Universities of China.
文摘Interlayer coupling in layered semiconductors can significantly affect their optoelectronic properties.However,understanding the mechanisms behind the interlayer coupling at the atomic level is not straightforward.Here,we study modulations of the electronic structure induced by the interlayer coupling in theγ-phase of indium selenide(γ-InSe)using scanning probe techniques.We observe a strong dependence of the energy gap on the sample thickness and a small effective mass along the stacking direction,which are attributed to strong interlayer coupling.In addition,the moirépatterns observed inγ-InSe display a small band-gap variation and nearly constant local differential conductivity along the patterns.This suggests that modulation of the electronic structure induced by the moirépotential is smeared out,indicating the presence of a significant interlayer coupling.Our theoretical calculations confirm that the interlayer coupling inγ-InSe is not only of the van der Waals origin,but also exhibits some degree of hybridization between the layers.Strong interlayer coupling might play an important role in the performance ofγ-InSe-based devices.
