分子束外延InAlSb红外探测器光电性能的温度效应

采用分子束外延生长方法在InSb （100）衬底上生长p+-p+-n-n+势垒型结构的In1-xAlxSb外延层。运用X射线衍射对材料的晶体质量及Al组分进行测试和表征,InAlSb外延层的半峰宽为0.05,表明外延材料的单晶性能良好,并通过布拉格方程和维戈定律计算出Al组分为2.5%。然后将外延材料制备成多元红外探测并测得77~210 K下的光谱响应曲线,实验发现探测器的截止波长从77 K时的4.48 m增加至210 K时的4.95 m。通过数据拟合得出In0.975Al0.025Sb禁带宽度的Varshni关系式以及其参数Eg（0）、和的值分别为0.238 6 eV,2.8710-4 eV/K,166.9 K。经I-V测试发现,在110 K,-0.1 V偏压下,器件的暗电流密度低至1.0910-5 A/cm-2,阻抗为1.40104 cm2,相当于77 K下InSb探测器的性能。同时分析了温度对器件不同类型的暗电流的影响程度,并得到器件的扩散电流与产生-复合电流的转变温度约为120 K。     

红外测量系统中光电导探测器电路设计

光电导探测器是一种常用的红外探测器件。文中介绍了其基本工作原理;选择光电导探测器的原则和依据;光电导探测器的偏置电路和前置放大电路的设计等。     

PbTe中红外光伏探测器

利用自主的分子束外延(MBE)技术在CdZnTe( 111)基底上生长PbTe半导体探测器材料,通过在PbTe薄膜上沉积In2 O3透明导电薄膜、ZnS绝缘保护层和In薄膜做电极,制成PbTe结型中红外光伏探测器.在77 K温度下,器件响应波长为1.5～5.5 μm,实验测量的探测率为2×1010 cm·Hz1/2W-...     

长波大面积HgCdTe光导红外探测器的研究

研制的长波大面积HgCdTe光导红外探测器的面积为2.1×2.1mm~2,在80K时探测率D_p~*=1.86×10~(10)cmHz~(1/2)W~(-1),响应率R_p=386VW~(-1),长波限λ_(co)(50%)>18μm.还研制了带有低温聚光器组合件结构的新型探测器,D_p~*=7.3×10~(10)cmHz~(1/2)W~(-1),λ_(co)(50%)>16μm.     

8～12μm光导多元红外探测器研制

本文通过对光导红外探测器的基本理论进行分析，给出了获得高性能红外探测器应具备的晶片参数和工艺设计的理论依据。实践证明，在此理论指导下开展长波线列光导器件研制，能重复制备出昏性能、高均命性的３２元、４８元和６０元红外探测器，其Ｄ￣＊＿ｂ＞１×１０￣（１０）ｃｍＨｚ￣（１／２）Ｗ￣（－１）、Ｒ＿Ｖ＞１×１０￣４ＶＷ￣（－１）、λ＿ｐ＞１１μｍ和λ＿ｃ＞１２μｍ。     

在分子束外延P型HgCdTe薄膜上制造长波红外平面光电二极管

本文介绍了分子束外延生长ＨｇＣｄＴｅ外延层以及利用平面工艺技术制制敏感波长为８μｍ－１０μｍ的小型ｐ－ｎ结的结果,在分子束外延过程中,生长动态,组分和表面粗糙度是利用内在高能电子衍射计和椭圆对称计在原位控制的。小面积光敏二极管（５０×７０μｍ）是利用平面工艺技术和阳极氧化物薄膜下的退火技术而制造出来的,Ｖ－Ｉ,光谱响应以及噪声特性的测量结果表明,在用发子束外延技术生长的碲镉汞外延层上制造的光电二极     

多光谱红外超像元光电探测器

美国专利US2004/0108564 (2004年6月10日公布) 在军事应用中,多光谱光电探测器可以用来探测经过伪装的目标和区分不同类型的目标。 本发明提供一种用于探测四个以上不同波段红外辐射的多光谱超像元光电探测器。该超像元光电探测     

量子响应高温超导薄膜红外探测器

基于超导探测器具有量子响应的实验论据，用量子理论导出高温超导薄膜探测器的，表明超导探测器的正比于超导薄膜长厚比的平方根，而与宽度无关。因此，采用超导薄膜（减小厚度），同时将薄膜光刻成弯曲线条或蛇形，增加其长度，将获得高Ｄ＊值的超导探测器。这是具有量子响应的超导探测器的重要结论。它为超导红外探测器的研制、设计提供了重要的理论依据。     

AlGaN基p-i-n光电探测器负响应现象研究

对AlGaN基p-i-n光电探测器的负光电响应特性进行研究,从实验上证实了器件中p型接触电极的肖特基特性是导致该现象的主导因素.不同偏压下的响应光谱表明,这些AlGaN光伏器件中存在较为明显的光导响应特性.光照和暗背景条件下的C-f曲线验证了器件中的持续光电导特性,而高铝组分铝镓氮材料内存在的大量缺陷被认为是该现象的起因.系统地研究了AlGaN基p-i-n光电探测器存在的负响应现象及其微观机理,为铝镓氮基日盲器件光电性能的优化提供了重要参考依据.     

InSb quantum dot LEDs grown by molecular beam epitaxy for mid-infrared applications

We report the molecular beam epitaxial growth of InSb quantum dots (QD) inserted as sub-monolayers in an InAs matrix which exhibit intense mid-infrared photoluminescence up to room temperature. The InSb QD sheets were formed by briefly exposing the surface to an antimony flux (Sb₂) exploiting an As-Sb anion exchange reaction. Light emitting diodes were fabricated using 10 InSb QD sheets and were found to exhibit bright electroluminescence with a single peak at 3.8 μm at room temperature.     

Long wavelength infra-red photoconductive InAsSb detectors grown in Si wells by molecular beam epitaxy

InAs/sub 0.05/Sb/sub 0.95/ photoconductive infra-red detectors have been grown by molecular beam epitaxy in recessed Si wells. The embedded devices exhibited a voltage responsivity of 420 V/W at 77 K and 300 meV photon energy with a load resistor of 100 Omega and a bias voltage of 1.5 V.<>     

Properties of Bi-doped PbTe layers grown by liquid phase epitaxy under controlled Te vapor pressure

Effects of Bi doping in PbTe liquid-phase epitaxial layers grown by the temperature difference method under controlled vapor pressure (TDM-CVP) are investigated. For Bi concentrations in the solution, x_Bi, lower than 0.2 at.%, an excess deep-donor level (activation energy E_d≈0.03–0.04 eV) appears, and Hall mobility is low. In contrast, for x_Bi>0.2 at.%, Hall mobility becomes very high, while carrier concentration is in the range of 10¹⁷ cm⁻³. Inductive coupled plasma (ICP) emission analysis shows that, for x_Bi=1 at.%, Bi concentration in the epitaxial layer is as high as N_Bi=2.3–2.7 × 10¹⁹ cm⁻³. These results indicate that Bi behaves not only as a donor but also as an acceptor, and the nearest neighbor or very near donor-acceptor (D-A) pairs are formed, so that strong self-compensation of Bi takes place. Carrier concentration for highly Bi-doped layers shows a minimum at a Te vapor pressure of 2.2 × 10⁻⁵ torr for growth temperature 470°C, which is coincident with that of the undoped PbTe.     

Lead-europium-selenide-telluride grown by molecular beam epitaxy

The band gap of lead-europium-telluride (Pb_1-x Eu_xTe) was determined from room temperature optical absorption measurements and increases as dEg/dx = 3.5 eV for x ≤ 0.044. Eu atoms bond strongly to a PbTe surface during MBE growth and have a small diffusion coefficient (<1 x 10⁻¹⁶ cm /sec at 370°C). The lattice constant of Pb_1-x, Eu_x Te is a nonlinear function of composition, and lattice-matched growth of Pb_1-x Eu_x Se_y Te_1-y, on PbTe is demonstrated. Preliminary studies of the electrical properties of Pb_1-x Eu_x Te indicate compensation of n-type (Bi) and p-type (Tl) dopants. These results indicate that Pb_1-x Eu_x Se_y Te_1-y, may be useful for obtaining diode lasers which emit at wavelengths shorter than those available from Pb_1-x, Sn_x Te.     

Minority carrier lifetime in indium-doped HgCdTe(211)B epitaxial layers grown by molecular beam epitaxy

We have studied the minority-carrier lifetime on intentionally indium-doped (211)B molecular beam epitaxially grown Hg_1-xCd_xTe epilayers down to 80K with x ≈ 23.0% ± 2.0%. Measured lifetimes were explained by an Auger-limited band-to-band recombination process in this material even in the extrinsic temperature region. Layers show excellent electron mobilities as high as ≈2 x 10⁵ cm²v^-1s^-1 at low temperatures. When the layers are compensated with Hg vacancies, results show that the Schockley-Read recombination process becomes important in addition to the band-to-band processes. From the values of τ_n0 and τ_p0 of one sample, the obtained defect level is acceptor-like and is somewhat related to the Hg vacancies.     

Variable area MWIR diodes on HgCdTe/Si grown by molecular beam epitaxy

Molecular beam epitaxy technique has been used to grow double layer heterostructure mercury cadmium telluride materials on silicon substrates for infrared detection in the mid-wavelength infrared transmission band. Test structures containing square diodes with variable areas from 5.76 × 10⁻⁶ cm² to 2.5×10⁻³ cm² are fabricated on them. The p on n planar architecture is achieved by selective arsenic ion implantation. The absorber layer characteristics for the samples studied here include a full width at half maximum of 100–120 arcsec from x-ray rocking curve, the electron concentration of 1−2 × 10¹⁵ cm⁻³ and mobility 3−5 × 10⁴ cm²/V-s, respectively at 80 K from Hall measurements. The minority carrier lifetime measured by photoconductive decay measurements at 80 K varied from 1 to 1.2 μsec. A modified general model for the variable area I–V analysis is presented. The dark current-voltage measurements were carried out at 80 K and an analysis of the dependence of zero-bias impedance on the perimeter/area ratio based on bulk, surface generation-recombination, and lateral currents are presented. The results indicate state-of-the art performance of the diodes in the midwavelength infrared region.     

Heteroepitaxy of HgCdTe (211)B on Ge substrates by molecular beam epitaxy for infrared detectors

Epitaxial growth of (211)B CdTe/HgCdTe has been achieved on two inch germanium (Ge) by molecular beam epitaxy (MBE). Germanium was chosen as an alternative substrate to circumvent the weaknesses of CdZnTe wafers. The ease of surface preparation makes Ge an attractive candidate among many other alternative substrates. Best MBE CdTe growth results were obtained on (211) Ge surfaces which were exposed to arsenic and zinc fluxes prior to the MBE growth. This surface preparation enabled CdTe growth with B-face crystallographic polarity necessary for the HgCdTe growth. This process was reproducible, and produced a smooth and mirror-like surface morphology. The best value of the {422} x-ray double diffraction full width at half maximum measured from the HgCdTe layer was 68 arc-s. We present the 486 point maps of FWHM statistical values obtained from CdTe/Ge and HgCdTe/CdTe/Ge. High resolution microscopy electron transmission and secondary ion mass spectroscopy characterization results are also presented in this paper. High-performance middle wavelength infrared HgCdTe 32-element photodiode linear arrays, using the standard LETI/LIR planar n-on-p ion implanted technology, were fabricated on CdTe/Ge substrates. At 78K, photodiodes exhibited very high R₀A figure of merit higher than 10⁶ Ωcm⁻² for a cutoff wavelength of 4.8 μm. Excess low frequency noise was not observed below 150K.     

Defect state assisted tunneling in intermediate temperature molecular beam epitaxy grown GaAs

Current transport in molecular beam epitaxy (MBE) GaAs grown at low and intermediate growth temperatures is strongly affected by defects. A model is developed here that shows that tunneling assisted by defect states can dominate, at some bias ranges, current transport in Schottky contacts to unannealed GaAs material grown at the intermediate temperature range of about 400°C. The deep defect states are modeled by quantum wells which trap electrons emitted from the cathode before re-emission to semiconductor. Comparison of theory with experimental data shows defect states of energies about 0.5 eVbelow conduction band to provide the best fit to data. This suggests that arsenic interstitials are likely to mediate this conduction. Comparison is also made between as-grown material and GaAs grown at the same temperature but annealed at 600°C. It is suggested that reduction of these defects by thermal annealing can explain lower current conduction at high biases in the annealed device as well as higher current conduction at low biases due to higher lifetime. Quenching of current by light in the as-grown material can also be explained based on occupancy of trap states. Identification of this mechanism can lead to its utilization in making ohmic contacts, or its elimination by growing tunneling barrier layers.     

Optical quality GaInAs grown by molecular beam epitaxy

Ga₄₇In₅₃As films have been grown by molecular beam epitaxy (MBE) on InP substrates. The unintentionally doped material has a free electron concentration of 8 × 10¹⁵cm^-3 and exhibits sharp (~5 meV linewidth) exciton recombination in the 4K photoluminescence. The films were grown on (100) InP surfaces which were thermally cleaned in the arsenic beam. The effects of the substrate temperature during growth, the Ga to In flux ratio and the group V to group III flux ratio on the 4K photoluminescence are reported.     

Wurtzite CdS on CdTe grown by molecular beam epitaxy

Growth of single crystal wurtzite cadmium sulfide on CdTe(111)B substrates has been achieved using molecular beam epitaxy. Reflection high-energy electron diffraction (RHEED) indicates smooth surface morphology for several hundreds of nanometers after nucleation. X-ray diffraction measurements confirm the crystalline orientation to be [0001] in the growth direction. X-ray photoelectron spectroscopy (XPS) indicates mostly stoichiometric CdS layers and the existence of a reaction at the interface. Sulfur incorporation into CdTe for various S fluxes has been investigated by Auger electron spectroscopy (AES). High-resolution TEM images of the interface between such epilayers were recorded. During the growth In was used as an in-situ dopant. The concentration and uniformity of In was determined by secondary ion mass spectrometry. Indium profiles were obtained for concentrations ranging from 5 × 10¹⁷ to 1.4 × 10²¹ cm⁻³. The experimental concentration agrees well with the variation expected from the In flux.