Hyperdoping that introduces impurities with concentrations exceeding their equilibrium solubility has been attract-ing great interest since the tuning of semiconductor properties increasingly relies on extreme measure...Hyperdoping that introduces impurities with concentrations exceeding their equilibrium solubility has been attract-ing great interest since the tuning of semiconductor properties increasingly relies on extreme measures.In this review we fo-cus on hyperdoped silicon(Si)by introducing methods used for the hyperdoping of Si such as ion implantation and laser dop-ing,discussing the electrical and optical properties of hyperdoped bulk Si,Si nanocrystals,Si nanowires and Si films,and present-ing the use of hyperdoped Si for devices like infrared photodetectors and solar cells.The perspectives of the development of hy-perdoped Si are also provided.展开更多
Polycrystalline Si(poly-Si)-based passivating contacts are promising candidates for high-efficiency crystalline Si solar cells.We show that nanosecond-scale pulsed laser melting(PLM)is an industrially viable technique...Polycrystalline Si(poly-Si)-based passivating contacts are promising candidates for high-efficiency crystalline Si solar cells.We show that nanosecond-scale pulsed laser melting(PLM)is an industrially viable technique to fabricate such contacts with precisely controlled dopant concentration profiles that exceed the solid solubility limit.We demonstrate that conventionally doped,hole-selective poly-Si/SiO_(x)contacts that provide poor surface passivation of c-Si can be replaced with Ga-or B-doped contacts based on non-equilibrium doping.We overcome the solid solubility limit for both dopants in poly-Si by rapid cooling and recrystallization over a timescale of∼25 ns.We show an active Ga dopant concentration of∼3×10^(20)cm^(−3)in poly-Si which is six times higher than its solubility limit in c-Si,and a B dopant concentration as high as∼10^(21) cm^(−3).We measure an implied open-circuit voltage of 735 mV for Ga-doped poly-Si/SiO_(x)contacts on Czochralski Si with a low contact resistivity of 35.5±2.4 mΩcm^(2).Scanning spreading resistance microscopy and Kelvin probe force microscopy show large diffusion and drift current in the p-n junction that contributes to the low contact resistivity.Our results suggest that PLM can be extended for hyperdoping of other semiconductors with low solubility atoms to enable high-efficiency devices.展开更多
Silicon-based photodetectors are experiencing significant demand for realizing infrared photodetection,night vision imaging,and ultraviolet-enhanced monitoring and communication.Recently,femtosecond-laser(fs-laser)hyp...Silicon-based photodetectors are experiencing significant demand for realizing infrared photodetection,night vision imaging,and ultraviolet-enhanced monitoring and communication.Recently,femtosecond-laser(fs-laser)hyperdoped silicon photodetectors have gained attention as promising alternatives to conventional silicon-based devices,owing to their exceptional properties,including high detectivity at low operating bias,broadband response spectrum beyond the bandgap limitation,wide operational temperature range,and ultrahigh dynamic range.Despite these advantages,the practical application of fs-laser hyperdoped devices has been hindered by challenges such as uneven surface structures and numerous lattice defects,which impede industrialization,chip integration,and ultraviolet photodetection performance.In this study,we present,to our knowledge,a novel design of flat fs-laser hyperdoped silicon materials and photodetectors tailored for complementary metal-oxide-semiconductor(CMOS)compatibility.A key innovation lies in the reduction of surface structure dimensions by three orders of magnitude,enabling the integration of fs-laser hyperdoped silicon as a photodetection layer in back-illuminated CMOS devices.The proposed photodetector achieves a peak responsivity of120.07 A/W and a specific detectivity of 1.27×10^(14)Jones at 840 nm,marking the highest performance reported for fs-laser hyperdoped silicon photodetectors.Furthermore,it demonstrates ultraviolet enhancement and sub-bandgap infrared photodetection simultaneously,with responsivities exceeding 10 A/W across a broad spectrum from 350 to 1170 nm at 5 V.This breakthrough not only paves the way for fs-laser hyperdoped silicon in array photodetection but also facilitates its integration with silicon-based chip fabrication processes,addressing critical bottlenecks for industrialization and advancing the field of silicon photonics.展开更多
Black silicon materials prepared via microstructuring and hyperdoping by ultrafast laser irradiation have attracted immense attention owing to their high absorption and photon sensitivity across a broadband spectral r...Black silicon materials prepared via microstructuring and hyperdoping by ultrafast laser irradiation have attracted immense attention owing to their high absorption and photon sensitivity across a broadband spectral range. However, a conflict exists between the repair requirements for the high amount of laser-induced damage and the thermally unstable hyperdoped impurities, resulting in low photon sensitivity and rapid decay at subbandgap wavelengths for the annealed black silicon. In this work, the properties of titanium(Ti) hyperdoped silicon have been explored using first-principle calculations.The findings of the study reveal that the interstitial Ti atoms exhibit a deep impurity band and low formation energy in silicon, which may be responsible for the stable subbandgap absorption that is achieved. Furthermore, femtosecond laser irradiation and rapid thermal annealing have been applied to manufacture Ti-hyperdoped black silicon(b-Si:Ti). The b-Si:Ti compound prepared by hyperdoping displayed high absorption across the visible and infrared ranges, with absorptance exceeding 90% for visible lights and 60% for subbandgap wavelengths. Additionally, the subbandgap absorption remains high even after intense thermal annealing, indicating a stable deep-level impurity of Ti in silicon. The experimental findings are consistent with the simulation results and complement each other to reveal the physical mechanisms responsible for the high performance of b-Si:Ti. The results thus demonstrate promising prospects for the application of black silicon in high-efficiency solar cells, photoelectric imaging, and flip-chip interconnection systems.展开更多
Developing a low-cost, room-temperature operated and complementary metal-oxide-semiconductor(CMOS)compatible visible-blind short-wavelength infrared(SWIR) silicon photodetector is of interest for security,telecommunic...Developing a low-cost, room-temperature operated and complementary metal-oxide-semiconductor(CMOS)compatible visible-blind short-wavelength infrared(SWIR) silicon photodetector is of interest for security,telecommunications, and environmental sensing. Here, we present a silver-supersaturated silicon(Si:Ag)-based photodetector that exhibits a visible-blind and highly enhanced sub-bandgap photoresponse. The visible-blind response is caused by the strong surface-recombination-induced quenching of charge collection for short-wavelength excitation, and the enhanced sub-bandgap response is attributed to the deep-level electrontraps-induced band-bending and two-stage carrier excitation. The responsivity of the Si:Ag photodetector reaches 504 mA · W^(-1) at 1310 nm and 65 m A · W^(-1) at 1550 nm under-3 V bias, which stands on the stage as the highest level in the hyperdoped silicon devices previously reported. The high performance and mechanism understanding clearly demonstrate that the hyperdoped silicon shows great potential for use in optical interconnect and power-monitoring applications.展开更多
基金supported by the National Key Research and Development Program of China (Grant Nos. 2017YFA0205704 and 2018YFB2200101)the Natural Science Foundation of China (Grant Nos. 91964107 and U20A20209)provided by the Natural Science Foundation of China for Innovative Research Groups (Grant No. 61721005)
文摘Hyperdoping that introduces impurities with concentrations exceeding their equilibrium solubility has been attract-ing great interest since the tuning of semiconductor properties increasingly relies on extreme measures.In this review we fo-cus on hyperdoped silicon(Si)by introducing methods used for the hyperdoping of Si such as ion implantation and laser dop-ing,discussing the electrical and optical properties of hyperdoped bulk Si,Si nanocrystals,Si nanowires and Si films,and present-ing the use of hyperdoped Si for devices like infrared photodetectors and solar cells.The perspectives of the development of hy-perdoped Si are also provided.
基金the National Renewable Energy Laboratory,operated by Alliance for Sustainable Energy,LLC,for the U.S.Department of Energy(DOE)under Contract No.DE-AC36-08GO28308.
文摘Polycrystalline Si(poly-Si)-based passivating contacts are promising candidates for high-efficiency crystalline Si solar cells.We show that nanosecond-scale pulsed laser melting(PLM)is an industrially viable technique to fabricate such contacts with precisely controlled dopant concentration profiles that exceed the solid solubility limit.We demonstrate that conventionally doped,hole-selective poly-Si/SiO_(x)contacts that provide poor surface passivation of c-Si can be replaced with Ga-or B-doped contacts based on non-equilibrium doping.We overcome the solid solubility limit for both dopants in poly-Si by rapid cooling and recrystallization over a timescale of∼25 ns.We show an active Ga dopant concentration of∼3×10^(20)cm^(−3)in poly-Si which is six times higher than its solubility limit in c-Si,and a B dopant concentration as high as∼10^(21) cm^(−3).We measure an implied open-circuit voltage of 735 mV for Ga-doped poly-Si/SiO_(x)contacts on Czochralski Si with a low contact resistivity of 35.5±2.4 mΩcm^(2).Scanning spreading resistance microscopy and Kelvin probe force microscopy show large diffusion and drift current in the p-n junction that contributes to the low contact resistivity.Our results suggest that PLM can be extended for hyperdoping of other semiconductors with low solubility atoms to enable high-efficiency devices.
基金supported by the National Key Research and Development Program of China(No.2024YFA1409500)the National Natural Science Foundation of China(Nos.12474344,12204141,and 62105362)the 111 Project(No.B23045)。
文摘Silicon-based photodetectors are experiencing significant demand for realizing infrared photodetection,night vision imaging,and ultraviolet-enhanced monitoring and communication.Recently,femtosecond-laser(fs-laser)hyperdoped silicon photodetectors have gained attention as promising alternatives to conventional silicon-based devices,owing to their exceptional properties,including high detectivity at low operating bias,broadband response spectrum beyond the bandgap limitation,wide operational temperature range,and ultrahigh dynamic range.Despite these advantages,the practical application of fs-laser hyperdoped devices has been hindered by challenges such as uneven surface structures and numerous lattice defects,which impede industrialization,chip integration,and ultraviolet photodetection performance.In this study,we present,to our knowledge,a novel design of flat fs-laser hyperdoped silicon materials and photodetectors tailored for complementary metal-oxide-semiconductor(CMOS)compatibility.A key innovation lies in the reduction of surface structure dimensions by three orders of magnitude,enabling the integration of fs-laser hyperdoped silicon as a photodetection layer in back-illuminated CMOS devices.The proposed photodetector achieves a peak responsivity of120.07 A/W and a specific detectivity of 1.27×10^(14)Jones at 840 nm,marking the highest performance reported for fs-laser hyperdoped silicon photodetectors.Furthermore,it demonstrates ultraviolet enhancement and sub-bandgap infrared photodetection simultaneously,with responsivities exceeding 10 A/W across a broad spectrum from 350 to 1170 nm at 5 V.This breakthrough not only paves the way for fs-laser hyperdoped silicon in array photodetection but also facilitates its integration with silicon-based chip fabrication processes,addressing critical bottlenecks for industrialization and advancing the field of silicon photonics.
基金supported by the National Natural Science Foundation of China (Nos.12204141,11974192,and 61875052)the Natural Science Foundation of Anhui Province (No.2208085QF214)the Fundamental Research Funds for the Central Universities (No.JZ2024HGTB0235)。
文摘Black silicon materials prepared via microstructuring and hyperdoping by ultrafast laser irradiation have attracted immense attention owing to their high absorption and photon sensitivity across a broadband spectral range. However, a conflict exists between the repair requirements for the high amount of laser-induced damage and the thermally unstable hyperdoped impurities, resulting in low photon sensitivity and rapid decay at subbandgap wavelengths for the annealed black silicon. In this work, the properties of titanium(Ti) hyperdoped silicon have been explored using first-principle calculations.The findings of the study reveal that the interstitial Ti atoms exhibit a deep impurity band and low formation energy in silicon, which may be responsible for the stable subbandgap absorption that is achieved. Furthermore, femtosecond laser irradiation and rapid thermal annealing have been applied to manufacture Ti-hyperdoped black silicon(b-Si:Ti). The b-Si:Ti compound prepared by hyperdoping displayed high absorption across the visible and infrared ranges, with absorptance exceeding 90% for visible lights and 60% for subbandgap wavelengths. Additionally, the subbandgap absorption remains high even after intense thermal annealing, indicating a stable deep-level impurity of Ti in silicon. The experimental findings are consistent with the simulation results and complement each other to reveal the physical mechanisms responsible for the high performance of b-Si:Ti. The results thus demonstrate promising prospects for the application of black silicon in high-efficiency solar cells, photoelectric imaging, and flip-chip interconnection systems.
基金National Natural Science Foundation of China(NSFC)(51532007,61574124,61721005)
文摘Developing a low-cost, room-temperature operated and complementary metal-oxide-semiconductor(CMOS)compatible visible-blind short-wavelength infrared(SWIR) silicon photodetector is of interest for security,telecommunications, and environmental sensing. Here, we present a silver-supersaturated silicon(Si:Ag)-based photodetector that exhibits a visible-blind and highly enhanced sub-bandgap photoresponse. The visible-blind response is caused by the strong surface-recombination-induced quenching of charge collection for short-wavelength excitation, and the enhanced sub-bandgap response is attributed to the deep-level electrontraps-induced band-bending and two-stage carrier excitation. The responsivity of the Si:Ag photodetector reaches 504 mA · W^(-1) at 1310 nm and 65 m A · W^(-1) at 1550 nm under-3 V bias, which stands on the stage as the highest level in the hyperdoped silicon devices previously reported. The high performance and mechanism understanding clearly demonstrate that the hyperdoped silicon shows great potential for use in optical interconnect and power-monitoring applications.
