Hg1-xCdxTe的共振拉曼散射

当入射光的光子能量接近Hg_1-xCd_xTe的E₀+Δ₀时,发现了Hg_1-xCd_xTe的共振拉曼散射,观察到了“禁戒”共振增强拉曼散射,同时也观察到了二级共振拉曼散射.分析了非共振条件下能在样品的(100)面观察到微弱的“禁戒”TO₂模以及在共振条件下“禁戒”TO₂模大大增强的原因.通过分析,发现由双LO声子引起的二级共振拉曼散射主要     

低温退火对HgCdTe中波光导器件γ辐照效应的影响

 研究了低温退火对HgCdTe中波光导探测器γ射线辐照效应的影响。经过剂量为1 Mrad的辐照后，器件的性能下降。对经过辐照的器件进行低温退火，退火温度范围为313～333 K，退火时间在5~16 h之间不等。在相同条件下测量了器件辐照前后及不同退火温度、不同退火时间下的体电阻、响应率、探测率和响应光谱。通过对比辐照前后及不同退火温度下性能参数的变化，分析了退火对器件的γ辐照效应的影响。实验表明：低温退火对辐照引起的性能的下降有一定的恢复作用。     

电子通量对ZnO/K2SiO3热控涂层光学性能的影响

 研究了电子通量对ZnO/K₂SiO₃热控涂层光学性能的影响。分别采用通量为5×10¹¹/cm²·s，8×10¹¹/cm²·s，1×10¹²/cm²·s 和5×10¹²/cm²·s的电子对试样进行辐照。电子辐照下涂层的光学性能发生了退化，并且发现了退化涂层在空气中的“漂白”现象。分析了ZnO/K₂SiO₃热控涂层光学性能的退化机制，同时讨论了电子通量对太阳光谱吸收系数的影响。实验结果发现，在5×10¹¹～1×10¹²/cm²·s的电子通量范围内，电子通量对ZnO/K₂SiO³热控涂层光学性能的影响相同。因此在这个电子通量范围内，采用加速地面试验来模拟空间的电子辐照效应是有效的。     

Hg1-xCdxTe外延薄膜的自由载流子吸收

讨论了Hg_1-xCd_xTe外延薄膜的自由载流子吸收光谱，分析了外延层的纵向组分分布及Ｔｅ沉淀物对吸收曲线的影响．结果表明，由于外延薄膜存在着纵向组分的不均匀性，其吸收特性与体材料有区别；对某些透过率较低的样品，则应考虑Ｔｅ沉淀物对吸收的贡献     

p-i-nInP/In_(0.53)Ga_(0.47)As/InP探测器结构优化

利用半导体仿真工具Silvaco对p-i-n InP/In_(0.53)Ga_(0.47)As/InP近红外光探测器进行优化仿真.参考实际器件对红外探测器进行建模,并将其暗电流、光谱响应仿真结果与实验结果进行拟合,保证仿真结果的有效性.以减小探测器的暗电流为目的,优化其结构.针对探测器吸收层厚度和吸收层掺杂浓度对暗电流、光响应的影响进行研究,发现当吸收层厚度大于0.3μm后,暗电流不再上升,但光响应随着吸收层厚度的增加而增大;当吸收层掺杂浓度不断上升时,器件暗电流不断降低,当掺杂浓度上升到2×1017/cm3时,暗电流达到最低值.本文还研究了p-i-n型探测器的瞬态响应,探究了响应速度与反偏电压之间的关系,发现提高反偏电压能减小探测器响应时间.     

Poly-Si1-xGex栅应变SiN型金属-氧化物-半导体场效应管栅耗尽模型研究

基于对Poly-Si_1-xGe_x栅功函数的分析,通过求解Poisson方程, 获得了Poly-Si_1-xGe_x栅应变Si N型金属-氧化物-半导体场效应器件 (NMOSFET)垂直电势与电场分布模型.在此基础上,建立了考虑栅耗尽的Poly-Si_1-xGe_x栅应变Si NMOSFET的阈值电压模型和栅耗尽宽度及其归一化模型,并利用该模型,对器件几何结构参数、 物理参数尤其是Ge组分对Poly-Si_1-xGe_x栅耗尽层宽度的影响, 以及栅耗尽层宽度对器件阈值电压的影响进行了模拟分析.结果表明:多晶耗尽随Ge组分和栅掺杂浓度的增加而减弱, 随衬底掺杂浓度的增加而增强;此外,多晶耗尽程度的增强使得器件阈值电压增大. 所得结论能够为应变Si器件的设计提供理论依据.     

应变Ge/Si1-xGex 价带色散模型

基于k·p微扰理论, 通过引入应变哈密顿量作为微扰, 建立了双轴应变Ge/Si_1-xGe_x价带色散关系模型. 模型适于任意晶向弛豫Si_1-xGe_x虚衬底上的应变Ge价带结构, 通过该模型可获得任意k方向应变Ge的价带结构和空穴有效质量. 模型的Matlab模拟结果显示, 应变Ge/Si_1-xGe_x价带带边空穴有效质量随Ge组分的增加而减小, 其各向异性比弛豫Ge更加显著. 本文研究成果对Si基应变Ge MOS器件及集成电路的沟道应力与晶向的设计有参考价值.     

基于PdSe2/GaAs异质结的高灵敏近红外光伏型探测器的制备和图像传感的应用

本文制备了一种基于PdSe₂/GaAs异质结的高灵敏近红外光电探测器，该探测器是通过将多层PdSe₂薄膜转移到平面GaAs上制成的. 所制备的PdSe₂/GaAs异质结器件在808 nm光照下表现出明显的光伏特性，这表明近红外光电探测器可以用作自驱动器件. 进一步的器件分析表明，这种杂化异质结在零偏电压和808 nm光照下具有1.16×10⁵的高开关比. 光电探测器的响应度和比探测度分别约为171.34 mA/W和2.36×10¹¹ Jones. 而且，该器件显示出优异的稳定性和可靠的重复性. 在空气中2个月后，近红外光电探测器的光电特性几乎没有下降，这归因于PdSe₂的良好稳定性. 最后，基于PdSe₂/GaAs的异质结器件还可以用作近红外光传感器.     

双光子吸收的Franz-Keldysh效应

从实验上证实Hg_0.695Cd_0.305Te 光电二极管空间电荷区中存在双光子吸收的Franz-Keldysh效应.利用一个皮秒Nd:YAG激光器抽运的光学参量产生器和差频产生器作为激发光源，测量了入射波长为λ₀=7.92μm的脉冲激光所激发的光响应随入射光强的变化关系.脉冲光响应峰值强度随入射光强的增大呈现二次幂函数增强趋势.采用等效RC电路模型将脉冲光伏信号峰值与入射光强相关联，得到空间电荷区中强电场下单光束     

碲镉汞焦平面光伏器件的实时γ辐照效应研究

对碲镉汞长波和中波焦平面光伏器件进行了实时γ射线辐照效应研究,通过辐照过程中实时测试器件的电流-电压特性,发现随着辐照剂量的增加,中波器件比长波器件表现出更好的抗辐照能力.对于长波器件,随着辐照剂量的增大,能够反映器件性能的零偏电阻逐渐降低;对于中波器件,零偏电阻随着辐照剂量的增加无固定变化趋势,辐照效应主要表现在电阻-电压曲线随着辐照剂量增加出现越来越明显的扰动.根据光伏器件的暗电流机理,对长波器件的电阻-电压曲线进行数值拟合,发现辐照引起少子产生-复合寿命逐渐降低,缺陷密度逐渐增大,主要影响的电流机理 关键词： γ辐照 辐照效应 光伏器件 碲镉汞     

Photodetectors,their performance and their limitations

With the human eye as a reference, a short survey of man-made photodetectors is given. The smallest number of detectable photons and the “detectivity” of present-day detectors, both as a function of the wavelength, are discussed in more detail. Finally, some special comments on the performance of photoconductive detectors are made since they are at present the most sensitive detectors for middle and far infrared radiation.     

Studying thermal performance of the PIN-photodiode photodetectors based on MGL and GNR

The novel approach proposed in the present study is to use graphene based materials in the structure of the available infrared photo detectors in order to improve their parameters. The photo detector under study is PIN photodiode photodetector with no internal gain, but a very wide wavelength. In this paper, we have shown that the graphene-based detectors can exhibit high responsivity and detectivity at elevated temperatures in a wide radiation spectrum due to high values of the quantum efficiency and relatively low rates of thermo generation which lead them to surpass other detectors substantially.     

Study on antireflective coatings of PbTe/PbSnTe heterojunction infrared detectors

ZnS antireflective coatings and passivation layer are developed on self-made PbTe/PbSnTe heterojunction infrared detectors and following experiments have been finished: WaterProof properties of ZnS coatings; Anti-reflective properties of PbSnTe materials and their detectors with ZnS coatings, respectively; ageing and stability tests of the PbSnTe detectors with ZnS coatings.All experimental results are excellent: The typical detectivity (D^*) of PbSnTe detector is 2.83×10¹⁰ cmHz^1/2W^–1. (with peak wavelength p=9.8 m and cut-off wavelength c=11.7 m). Average detectivity of the PbSnTe detector with ZnS anti-reflective coatings is increased by 45%. Ageing tests indicated that the PbSnTe detectors with ZnS coatings have still high stabilities after several years. They are used successfully in medical infrared imaging systems and other applications.     

Type-II superlattice detectors for free space optics applications and higher operating temperature conditions

The utmost limit performance of interband cascade detectors optimized for the longwave range of infrared radiation is investigated in this work. Currently, materials from the III–V group are characterized by short carrier lifetimes limited by Shockley-Read-Hall generation and recombination processes. The maximum carrier lifetime values reported at 77 K for the type-II superlattices InAs/GaSb and InAs/InAsSb in a longwave range correspond to ～200 and ～400 ns. We estimated theoretical detectivity of interband cascade detectors assuming above carrier lifetimes and a value of ～1–50 μs reported for a well-known HgCdTe material. It has been shown that for room temperature the limit value of detctivity is of ～3–4×10¹⁰ cmHz^1/2/W for the optimized detector operating at the wavelength range ～10 μm could be reached.     

Sulphur-doped silicon background-limited infrared photodetectors near 77 K

The photoconductive properties of sulphur-doped extrinsic silicon infrared detectors prepared by closed-tube diffusion techniques have been investigated. Spectral response data show that this material would be suitable for thermal imaging of 3–5 μm radiation, whilst detectivity measurements as a function of temperature indicate that background-limited operation is achievable near liquid nitrogen temperature (77 K).     

Terahertz and infrared photodetectors based on multiple graphene layer and nanoribbon structures

We consider new concepts of terahertz and infrared photodetectors based on multiple graphene layer and multiple graphene nanoribbon structures and we evaluate their responsivity and detectivity. The performance of the detectors under consideration is compared with that of photodetectors made of the traditional structures. We show that due to high values of the quantum efficiency and relatively low rates of thermogeneration, the graphene-based detectors can exhibit high responsivity and detectivity at elevated temperatures in a wide radiation spectrum and can substantially surpass other detectors. The detector being discussed can be used in different wide-band and multi-colour terahertz and infrared systems.     

Intersubband transitions in quantum well mid-infrared photodetectors

A study of intersubband transitions in quantum well infrared detectors working at high temperatures has been reported. This study allows a greater tunability in the device designs, with the ability to control the peak wavelength, the absorption coefficient, the dark current, the quantum efficiency and the detectivity of the modeled structure operating around 3.3 μm wavelength. The detection energy and absorption coefficient dependences with an applied electric field are given. Then, the electro-optic performances of the modeled mid-infrared detector are estimated, the dark current dependence with the applied voltage and temperature as well as the quantum efficiency and the detectivity are investigated and discussed. High detectivities were found at high temperatures revealing the good performances of the designed photodetector, especially at 3.3 μm wavelength.     

Photoluminescence measurements of LiF TL detectors

The properties of standard lithium fluoride (LiF) thermoluminescent (TL) detectors, which are routinely used in radiation protection systems, were investigated under light stimulation. The luminescence of different types of LiF detectors, which were irradiated with gamma rays of energy up to 300 Gy and alpha particles with a fluence up to 5*10⁹ cm⁻², were stimulated by a blue light and were heated up to temperature of 240 °C or 400 °C, depending on the type of detectors. The irradiated LiF detectors during the blue-light (460 nm) stimulation emit green photoluminescence (PL) with a wavelength of 530 nm. The LiF detectors showed a PL effect of much higher efficiency after they were irradiated with alpha particles than after they were irradiated with gamma rays. However, in contrast to PL, the TL readout showed a significantly lower efficiency of LiF detectors after alpha particle irradiation. These effects result from the different trap mechanisms that are responsible for TL and PL phenomena. The temperature stability of the traps responsible for the PL effect for both types of LiF detectors was studied.