High-performance and tensile-strained germanium （Ge） p-i-n photodetector is demonstrated on Si substrate. The epi- taxial Ge layers were prepared in an ultrahigh vacuum chemical vapor deposition （UHV-CVD） system u...High-performance and tensile-strained germanium （Ge） p-i-n photodetector is demonstrated on Si substrate. The epi- taxial Ge layers were prepared in an ultrahigh vacuum chemical vapor deposition （UHV-CVD） system using low tem- perature Ge buffer technique. The devices were fabricated by in situ doping and using Si as passivation layer between Ge and metal, which can improve the ohmic contact and realize the high doping. The results show that the dark current of the photodetector with diameter of 24 lain is about 2.5 × 10.7 μA at the bias voltage of-1 V, and the optical responsivity is 0.1 A/W at wavelength of 1.55 μm. The 3 dB bandwidth （BW） of 4 GHz is obtained for the photodetector with diameter of 24 μm at reverse bias voltage of 1 V. The long diffusion time of minority carrier in n-type Ge and the large contact resistance in metal/Ge contacts both affect the performance of Ge photodetectors.展开更多
An understanding of the absorption of light is essential for efficient photovoltaic and photodetection applications with III-V nanowire arrays. Here, we correlate experiments with modeling and verify experimentally th...An understanding of the absorption of light is essential for efficient photovoltaic and photodetection applications with III-V nanowire arrays. Here, we correlate experiments with modeling and verify experimentally the predicted absorption of light in InP nanowire arrays for varying nanowire diameter and length. We find that 2,000 nm long nanowires in a pitch of 400 nm can absorb 94% of the incident light with energy above the band gap and, as a consequence, light which in a simple ray-optics description would be travelling between the nanowires can be efficiently absorbed by the nanowires. Our measurements demonstrate that the absorption for long nanowires is limited by insertion reflection losses when light is coupled from the air top-region into the array. These reflection losses can be reduced by introducing a smaller diameter to the nanowire-part closest to the air top-region. For nanowire arrays with such a nanowire morphology modulation, we find that the absorptance increases monotonously with increasing diameter of the rest of the nanowire.展开更多
Using two-step growth method and buffer layer annealing treatment,the double heterojunction structures of In_(0.82)Ga_(0.18) As epilayer capped with In As_(0.6)P0.4 layer were prepared on In P substrate by low pressur...Using two-step growth method and buffer layer annealing treatment,the double heterojunction structures of In_(0.82)Ga_(0.18) As epilayer capped with In As_(0.6)P0.4 layer were prepared on In P substrate by low pressure metal organic chemical vapor deposition(LP-MOCVD).Based on the high quality In_(0.82)Ga_(0.18) As structures,the In_(0.82)Ga_(0.18) As PIN photodetector with cut-off wavelength of 2.56 μm at room temperature was fabricated by planar semiconductor technology,and the device performance was investigated in detail.The typical dark current at the reverse bias VR=10 m V and the resistance area product R0 A are 5.02 μA and 0.29 ?·cm2 at 296 K and 5.98 n A and 405.2 ?·cm2 at 116 K,respectively.The calculated peak detectivities of the In_(0.82)Ga_(0.18) As photodetector are 1.21×1010 cm·Hz1/2/W at 296 K and 4.39×1011 cm·Hz1/2/W at 116 K respectively,where the quantum efficiency η=0.7 at peak wavelength is supposed.The results show that the detection performance of In_(0.82)Ga_(0.18) As prepared by two-step growth method can be improved greatly.展开更多
基金supported by the USTC Research Funds of the Double First-Class Initiative(YD3480002002)the USTC Center for Micro and Nanoscale Research and Fabrication。
基金supported by the National Natural Science Foundation of China(Nos.61474094 and 61176092)
文摘High-performance and tensile-strained germanium （Ge） p-i-n photodetector is demonstrated on Si substrate. The epi- taxial Ge layers were prepared in an ultrahigh vacuum chemical vapor deposition （UHV-CVD） system using low tem- perature Ge buffer technique. The devices were fabricated by in situ doping and using Si as passivation layer between Ge and metal, which can improve the ohmic contact and realize the high doping. The results show that the dark current of the photodetector with diameter of 24 lain is about 2.5 × 10.7 μA at the bias voltage of-1 V, and the optical responsivity is 0.1 A/W at wavelength of 1.55 μm. The 3 dB bandwidth （BW） of 4 GHz is obtained for the photodetector with diameter of 24 μm at reverse bias voltage of 1 V. The long diffusion time of minority carrier in n-type Ge and the large contact resistance in metal/Ge contacts both affect the performance of Ge photodetectors.
文摘An understanding of the absorption of light is essential for efficient photovoltaic and photodetection applications with III-V nanowire arrays. Here, we correlate experiments with modeling and verify experimentally the predicted absorption of light in InP nanowire arrays for varying nanowire diameter and length. We find that 2,000 nm long nanowires in a pitch of 400 nm can absorb 94% of the incident light with energy above the band gap and, as a consequence, light which in a simple ray-optics description would be travelling between the nanowires can be efficiently absorbed by the nanowires. Our measurements demonstrate that the absorption for long nanowires is limited by insertion reflection losses when light is coupled from the air top-region into the array. These reflection losses can be reduced by introducing a smaller diameter to the nanowire-part closest to the air top-region. For nanowire arrays with such a nanowire morphology modulation, we find that the absorptance increases monotonously with increasing diameter of the rest of the nanowire.
基金supported by the National Natural Science Foundation of China(Nos.11174224 and 11404246)the Natural Science Foundation of Shandong Province(Nos.BS2015DX015 and ZR2013FM001)+1 种基金the Science and Technology Development Program of Shandong Province(No.2013YD01016)the Higher School Science and Technology Program of Shandong Province(Nos.J13LJ54 and J15LJ54)
文摘Using two-step growth method and buffer layer annealing treatment,the double heterojunction structures of In_(0.82)Ga_(0.18) As epilayer capped with In As_(0.6)P0.4 layer were prepared on In P substrate by low pressure metal organic chemical vapor deposition(LP-MOCVD).Based on the high quality In_(0.82)Ga_(0.18) As structures,the In_(0.82)Ga_(0.18) As PIN photodetector with cut-off wavelength of 2.56 μm at room temperature was fabricated by planar semiconductor technology,and the device performance was investigated in detail.The typical dark current at the reverse bias VR=10 m V and the resistance area product R0 A are 5.02 μA and 0.29 ?·cm2 at 296 K and 5.98 n A and 405.2 ?·cm2 at 116 K,respectively.The calculated peak detectivities of the In_(0.82)Ga_(0.18) As photodetector are 1.21×1010 cm·Hz1/2/W at 296 K and 4.39×1011 cm·Hz1/2/W at 116 K respectively,where the quantum efficiency η=0.7 at peak wavelength is supposed.The results show that the detection performance of In_(0.82)Ga_(0.18) As prepared by two-step growth method can be improved greatly.
