Ultrasonic-assisted synthesis of ZnTe nanostructures and their structural,electrochemical and photoelectrical properties

Colloidal zinc telluride (ZnTe) nanostructures were successfully processed through a simple and facile ultrasonic (sonochemical) treatment for photoelectronic applications. The particle-like morphological features, phase and nature of valence state of various metal ions existing in ZnTe were examined using electron and X-ray photoelectron spectroscopic tools. Raman spectroscopic measurements revealed the dominance of exciton-phonon coupling and occurrence of TeO₂ traces in ZnTe through the corresponding vibrations. Optical bandgap of the ZnTe suspension was estimated to be around 2.15 eV, authenticating the direct allowed transitions. The p-type electrical conductivity and charge carrier density of ZnTe were additionally estimated from the Bode, Nyquist and Mott-Schottky type impedance plots. The photoelectrical properties of ZnTe were investigated by fabricating p-ZnTe/n-Si heterostructures and studying their corresponding current-voltage characteristics under dark and white light illumination. The diodes revealed excellent rectifying behaviour with significant increase in reverse current under illumination. The stability of the devices were also affirmed through the time-dependent photoresponse characteristics, which actually suggested the improved and effective separation of photo generated electron hole pairs across the integrated heterojunctions. The obtained results also augment the potential of sonochemically processed ZnTe for application in photo detection and sensor related functions.     

Study on Photocapacitance in PN Junction of High Resistivity P—type Silicon

１ＩｎｔｒｏｄｕｃｔｉｏｎＷｉｔｈｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｐｕｒｉｆｉｃａｔｉｏｎａｎｄｇｒｏｗｔｈｏｆｓｉｌｉｃｏｎｍａｔｅｒｉａｌ，ｅｓｐｅｃｉａｌｙ，ｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｈｉｇｈｌｙｐｕｒｅＳｉＨ４，ｔｈｅｐｕｒｉｔｙｏｆｈ...     

Anomalous I–V and pulse noise in reverse biased p–n junctions

A correlation between anomalous I-V characteristics and pulse noise in degraded p-n junctions under reverse bias conditions is found. In order to explain the appearance of two-polarity and multi-level pulse noise, a physical model of noise sources is proposed. The model is based on the presumptions that conduction channels and a p-inversion layer exist in degraded p-n junctions and that the current flow through the defects is modulated by traps adjacent to the defects. The experimental results for silicon field plated PIN photodiodes are in qualitative agreement with the model.     

Oxide removal from the GaSb surface and fabrication of MBE GaSb photodiodes and Au–GaSb schottky diodes

Oxide removal from GaSb surfaces by several wet chemical treatments and subsequent thermal annealing was investigated. Preferable wet chemical treatments by which surface oxides could be removed effectively at room temperature were evaluated in the experiments. This method can be effectively applied to fabrication processing of MBE GaSb photodoides and Au–GaSb Schottky doides. Low-reverse-leakage GaSb photodiodes and near ideal Au–GaSb Schottky diodes were thus obtianed.     

高阻P型硅PN结中的光电转换

用高阻Ｐ型硅（ρ＝１２０００Ω·ｃｍ）单晶材料制作了ＰＮ结光敏二极管，对二极管的光电参数进行了测量。在激光辐射下，测出样管在光照前后的Ｃ－Ｖ实验曲线及样管在光照前后的电容相对变化可达到１００％，远大于低阻Ｐ型硅ＰＮ结在光照前后电容的相对变化率，并得到雾偏下样管电容在光照前后的相对变化率为１２１．７％。     

硅光电二极管快中子和氧离子的辐照效应

研究了硅光电二极管经快中子（注入剂量为１０＾１１ｃｍ＾－２，能量２．４５ＭｅＶ）和Ｏ＾＋＋＋（注入剂量为１０＾１０ｃｍ＾－２，能量１２ＭｅＶ）辐照后光电参数的变化规律，并通过光谱光电流的变化，对辐照损伤的空间分布进行了分析。结果表明，两种辐照垃引起器件的光电流下降，暗电流增加，在本实验条件下，快中子造成的损伤轻微且均匀地分布在整个器件体内，而Ｏ＾＋＋＋，辐照损伤区集中在器件表面附近，其损伤国快中子     

砷注入碲镉汞P—on—N结的电流电压特性

最近,选用Ｎ 型体材料碲镉汞（Ｈｇ１－ ｘＣｄｘＴｅ） 作衬底,成功制备了平面ＰｏｎＮ 结构的光电二极管。文中报道了制备各个波段ＰｏｎＮ 结的一些进展。碲镉汞平面ＰｏｎＮ 结采用砷掺杂在Ｎ 型衬底上形成Ｐ区,砷掺杂由砷离子注入加上退火扩散形成。对ＰｏｎＮ 二极管的电流电压关系温度特性的研究表明：直到１４０Ｋ,长波（λｃ ＝ ９ ．１μｍ）ＰｏｎＮ 结的暗电流以扩散电流为主。制备了从中波到长波各个波段的碲镉汞ＰｏｎＮ 结构红外探测器。目前,对于λｃ ＝ ５ ．２μｍ 的器件,Ｒ０ Ａ 值达到６８Ωｃｍ２ ,黑体探测率Ｄ＊ｂｂ（５００Ｋ） 可达２ ×１０１０ｃｍ Ｈｚ１／２／ Ｗ;对于λｃ ＝ １４ ．５μｍ 的器件,Ｒ０ Ａ 值达到０－２Ωｃｍ２ ,黑体探测率Ｄ＊ｂｂ（５００Ｋ） 可达１ ×１０９ｃｍ Ｈｚ１／２／ Ｗ。     

点状PN结中的光电转换

用Ｎ型硅单晶材料制作了点状ＰＮ结光电二极管，对二极管的光电参数进行了测量。若依平面结的受光面积计算，在同样的光辐射下，点状ＰＮ结光岂二极管的光电流密度是常规面积光电二极管光电流密度的２００倍以上。分析表明，在光探测机制上不仅要考虑平面结范围内的光电转换，更要考虑平面结周边一个少数载流子扩散长度范围内的光电转换。利用点状ＰＮ结光照电流的测量，可以 确定在衬底材料光一少了的扩散长度。     

Evaluation of the full operational cycle of a CMOS transfer-gated photodiode active pixel

In this paper we evaluate the full operational cycle of the active-pixel circuit for CMOS image sensors in which four field-effect transistors are suitably combined with an ordinary photodiode; meaning a vertical p–n junction, as opposed to photogates, and with no custom pinned layer. Although this circuit topology itself is not novel, this evaluation intends to shine new light on the use of regular photodiodes. They became largely in disuse in four-transistor image chips under earlier process and design circumstances because the fourth transfer-gate FET did not hold a constant signal long enough and not for a fixed time. Our aim is to investigate the full underlying operational regimen of the transfer gate to propose that a regular photodiode might again be a choice to consider in the four-transistor pixel configuration, not only in conventional imaging but also in dedicated optical applications. The use of an ordinary p–n junction photodiode is advantageous as it offers full compatibility with even elementary mainstream CMOS processes. This investigation resorts to experiments and models both with fabricated integrated pixels and with a macro-pixel circuit implementation.     

高帧速自扫描光电二极管面阵

通过对多路并行输出的高帧速自扫描光电二极管面阵（ＳＳＰＡ）的研究，分析了影响面阵帧速和响应度的主要因素。设计并制作出３２×３２位多路并行输出的ＳＳＰＡ实验样品。其性能参数为：ＦＰＳ（帧速）≤２０００帧／秒时，Ｖｏｓ（最大输出电压）＝２４０ｍＶ，Ｒ（响应度）＝１．０９Ｖ·１ｘ－１·ｓ－１；ＦＰＳ＝１００００帧／秒时，Ｖｏｓ＝１５０ｍＶ；ＦＰＳ＝１５０００帧／秒时，Ｖｏｓ＝１００ｍＶ。