A very long wavelength infrared(VLWIR) focal plane array based on In As/Ga Sb type-Ⅱ super-lattices is demonstrated on a Ga Sb substrate. A hetero-structure photodiode was grown with a 50% cut-off wavelength of 15.2 ...A very long wavelength infrared(VLWIR) focal plane array based on In As/Ga Sb type-Ⅱ super-lattices is demonstrated on a Ga Sb substrate. A hetero-structure photodiode was grown with a 50% cut-off wavelength of 15.2 μm, at 77 K.A 320×256 VLWIR focal plane array with this design was fabricated and characterized. The peak quantum efficiency without an antireflective coating was 25.74% at the reverse bias voltage of-20 mV, yielding a peak specific detectivity of 5.89×1010cm·Hz^(1/2)·W^(-1). The operability and the uniformity of response were 89% and 83.17%. The noise-equivalent temperature difference at 65 K exhibited a minimum at 21.4 mK, corresponding to an average value of 56.3 mK.展开更多
In this paper,multilayer antireflection coatings are designed by modifying the thickness of two and three paired layer distributed Bragg reflector(DBR)structure.Our proposed DBR-based structures show antireflection be...In this paper,multilayer antireflection coatings are designed by modifying the thickness of two and three paired layer distributed Bragg reflector(DBR)structure.Our proposed DBR-based structures show antireflection behaviors,in spite of the reflection treatment in traditional DBR structures.Firstly,the proposed structures are designed to be equivalent to the theoretical ideal triple-layer(TL)antireflection coating(ARC).Therefore,the problem of finding a suitable material for the middle layer of triple structure is solved.Simulation results show the significant equivalency for the reflectance of proposed structures to the ideal TL ARC at the same wavelengths and incident angles.Also,the design of the structure is changed in order to present the constant reflectance coefficient over a wide range of wavelengths.This structure enhances the omni-directionality of the multilayer ARC.展开更多
We suggest a design method of graded-refractive-index (GRIN) antireflection (AR) coating for s-polarized or ppolarized light at off-normal incidence.The spectrum characteristic of the designed antireflection coating w...We suggest a design method of graded-refractive-index (GRIN) antireflection (AR) coating for s-polarized or ppolarized light at off-normal incidence.The spectrum characteristic of the designed antireflection coating with a quintic effective refractive-index profile for a given state of polarization has been discussed.In addition,the genetic algorithm was used to optimize the refractive index profile of the GRIN antireflection for reducing the mean reflectance of s-and p-polarizations.The average reflectance loss was reduced to only 0.04% by applying optimized GRIN AR coatings onto BK7 glass over the wavelength range from 400 to 800 nm at the incident angle of θ 0=70°.展开更多
A p-i-i-n type AlG a N heterostructure avalanche photodiodes(APDs)is proposed to decrease the avalanche breakdown voltage and to realize higher gain by using high-Al-content AlG aN layer as multiplication layer and lo...A p-i-i-n type AlG a N heterostructure avalanche photodiodes(APDs)is proposed to decrease the avalanche breakdown voltage and to realize higher gain by using high-Al-content AlG aN layer as multiplication layer and low-Al-content AlG aN layer as absorption layer.The calculated results show that the designed APD can significantly reduce the breakdown voltage by almost 30%,and about sevenfold increase of maximum gain compared to the conventional Al GaN APD.The noise in designed APD is also less than that in conventional APD due to its low dark current at the breakdown voltage point.Moreover,the one-dimensional(1D)dual-periodic photonic crystal(PC)with anti-reflection coating filter is designed to achieve the solar-blind characteristic and cutoff wavelength of 282 nm is obtained.展开更多
This paper reports that stoichiometric, amorphous, and uniform Er2O3 films are deposited on Si(001) substrates by a radio frequency magnetron sputtering technique. Ellipsometry measurements show that the refractive in...This paper reports that stoichiometric, amorphous, and uniform Er2O3 films are deposited on Si(001) substrates by a radio frequency magnetron sputtering technique. Ellipsometry measurements show that the refractive index of the Er2O3 films is very close to that of a single layer antireflection coating for a solar cell with an air surrounding medium during its working wavelength. For the 90-nm-thick film, the reflectance has a minimum lower than 3% at the wavelength of 600 nm and the weighted average reflectances (400-1000 nm) is 11.6%. The obtained characteristics indicate that Er2O3 films could be a promising candidate for antireflection coatings in solar cells.展开更多
基金supported by the National Basic Research Program of China(Grant Nos.2013CB932904 and 2011CB922201)the National Special Funds for the Development of Major Research Equipment and Instruments,China(Grant No.2012YQ140005)the National Natural Science Foundation of China(Grant Nos.61274013,61290303,and 61306013)
文摘A very long wavelength infrared(VLWIR) focal plane array based on In As/Ga Sb type-Ⅱ super-lattices is demonstrated on a Ga Sb substrate. A hetero-structure photodiode was grown with a 50% cut-off wavelength of 15.2 μm, at 77 K.A 320×256 VLWIR focal plane array with this design was fabricated and characterized. The peak quantum efficiency without an antireflective coating was 25.74% at the reverse bias voltage of-20 mV, yielding a peak specific detectivity of 5.89×1010cm·Hz^(1/2)·W^(-1). The operability and the uniformity of response were 89% and 83.17%. The noise-equivalent temperature difference at 65 K exhibited a minimum at 21.4 mK, corresponding to an average value of 56.3 mK.
文摘In this paper,multilayer antireflection coatings are designed by modifying the thickness of two and three paired layer distributed Bragg reflector(DBR)structure.Our proposed DBR-based structures show antireflection behaviors,in spite of the reflection treatment in traditional DBR structures.Firstly,the proposed structures are designed to be equivalent to the theoretical ideal triple-layer(TL)antireflection coating(ARC).Therefore,the problem of finding a suitable material for the middle layer of triple structure is solved.Simulation results show the significant equivalency for the reflectance of proposed structures to the ideal TL ARC at the same wavelengths and incident angles.Also,the design of the structure is changed in order to present the constant reflectance coefficient over a wide range of wavelengths.This structure enhances the omni-directionality of the multilayer ARC.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10704079 and 10976030)
文摘We suggest a design method of graded-refractive-index (GRIN) antireflection (AR) coating for s-polarized or ppolarized light at off-normal incidence.The spectrum characteristic of the designed antireflection coating with a quintic effective refractive-index profile for a given state of polarization has been discussed.In addition,the genetic algorithm was used to optimize the refractive index profile of the GRIN antireflection for reducing the mean reflectance of s-and p-polarizations.The average reflectance loss was reduced to only 0.04% by applying optimized GRIN AR coatings onto BK7 glass over the wavelength range from 400 to 800 nm at the incident angle of θ 0=70°.
基金supported by Anhui University Natural Science Research Project, China (KJ2015A153)Initial research fund from Chuzhou University, China (2014qd024)+1 种基金The Higher Education Excellent Youth Talents Foundation of Anhui Province (gxyqZ D2016329)the Anhui Provincial Natural Science Foundation of China under Grant (1708085MF149)
文摘A p-i-i-n type AlG a N heterostructure avalanche photodiodes(APDs)is proposed to decrease the avalanche breakdown voltage and to realize higher gain by using high-Al-content AlG aN layer as multiplication layer and low-Al-content AlG aN layer as absorption layer.The calculated results show that the designed APD can significantly reduce the breakdown voltage by almost 30%,and about sevenfold increase of maximum gain compared to the conventional Al GaN APD.The noise in designed APD is also less than that in conventional APD due to its low dark current at the breakdown voltage point.Moreover,the one-dimensional(1D)dual-periodic photonic crystal(PC)with anti-reflection coating filter is designed to achieve the solar-blind characteristic and cutoff wavelength of 282 nm is obtained.
基金supported by the Special Project of Shanghai Nano-technology (Grant No.0852nm02400)the National Natural Science Foundation of China (Grant Nos.10804072 and 60806031)the Key Fundamental Project of Shanghai (GrantNo.08JC1410400)
文摘This paper reports that stoichiometric, amorphous, and uniform Er2O3 films are deposited on Si(001) substrates by a radio frequency magnetron sputtering technique. Ellipsometry measurements show that the refractive index of the Er2O3 films is very close to that of a single layer antireflection coating for a solar cell with an air surrounding medium during its working wavelength. For the 90-nm-thick film, the reflectance has a minimum lower than 3% at the wavelength of 600 nm and the weighted average reflectances (400-1000 nm) is 11.6%. The obtained characteristics indicate that Er2O3 films could be a promising candidate for antireflection coatings in solar cells.
