GaAs基RTD与MSM光电集成

报道了GaAs基共振隧穿二极管(RTD)与金属-半导体-金属光电探测器(MSM PD)单片集成的两种光电集成电路,并在室温条件下分别测试了RTD器件、MSM器件和集成电路的电学特性.测试表明:RTD器件的峰谷电流比为4;由于改进了在半绝缘GaAs衬底上制作MSM的方法,5V偏压下的电流由原来的2μA增加到了18μA,基本实现了两种电路的逻辑功能.     

Monolithically Fabricated OEICs Using RTD and MSM

报道了GaAs基共振隧穿二极管(RTD)与金属-半导体-金属光电探测器(MSM PD)单片集成的两种光电集成电路,并在室温条件下分别测试了RTD器件、MSM器件和集成电路的电学特性.测试表明:RTD器件的峰谷电流比为4;由于改进了在半绝缘GaAs衬底上制作MSM的方法,5V偏压下的电流由原来的2μA增加到了18μA,基本实现了两种电路的逻辑功能.     

4H-SiC紫外光电探测器光电特性随温度变化的研究

利用光电流谱法研究了300K到60K温度范围内的p-i-n结构4H-SiC紫外光电探测器的暗电流及相对光谱响应特性。研究发现随着温度的降低,探测器的暗电流和相对光谱响应都逐渐减小;而且,反向偏压越高,暗电流减小的速率越大。在零偏压下,随着温度的降低,器件的温度从300K降低到60K时,相对光谱响应的峰值波长先向短波方向移动,后向长波方向移动,在60K时移至从272nm附近移至282nm附近;同时观察到探测器的相对光谱响应范围略有缩小,。此外,我们对器件并讨论了温度变化对器件p、i、n各层产生的光电流随温度变化的机理进行讨论,提出了可以通过减少i层缺陷和适当减小n层的掺杂浓度的方式来提高器件的相对光谱响应。     

中波-长波双色量子阱红外探测器

采用n型掺杂的AlGaAs/GaAs和AlGaAs/InGaA多量子阱材料,基于MOCVD外延生长技术,利用成熟的GaAs集成电路加工工艺,设计并制作了不同结构的中波-长波双色量子阱红外探测器(QWIP)器件,器件采用正面入射二维光栅耦合,光栅周期设计为4μm,宽度2μm;对制作的500μm×500μm大面积双色QWIP单元器件暗电流、响应光谱、探测率进行了测试和分析。在-3V偏压、77K温度和300K背景温度下长波(LWIR)和中波(MWIR)QWIP的暗电流密度分别为0.6、0.02mA/cm2;-3V偏压、80K温度下MWIR和LWIR QWIP的响应光谱峰值波长分别为5.2、7.8μm;在2V偏压、65K温度下,LWIR和MWIR QWIP的峰值探测率分别为1.4×1011、6×1010cm.Hz1/2/W。     

GaAs/InGaAs量子点探测器件微光读出研究

GaAs/InGaAs量子点光电探测器,在633 nm激光辐射3.5 nW条件下,器件偏压-1.4 V时,测得响应电流8.9×10-9A,电流响应率达到2.54 A/W,量子注入效率超过90%。基于GaAs/InGaAs量子点光电探测器的高量子注入效率、高灵敏度等特点,采用具有稳定的电压偏置,高注入效率和低噪声特点的CTIA(电容互阻跨导放大器)作为列放大器读出结构,输出部分采用相关双采样(CDS)结构去除系统和背景噪声。实验结果表明,在3.5 nW的微光辐射下,器件偏压为-2.5 V时,50μm×50μm像素探测器与读出电路互联后有7.14×107V/W的电压响应率。     

GaN基MSM结构紫外探测器光响应特性

在求解一维电流连续性方程和传输方程的同时考虑表面态陷阱的作用,获得了GaN基MSM结构紫外探测器在稳态光照下的电流随电压变化的解析解,从而导出了其光响应特性主要参数,并解释了电流和响应度随偏压变化的原因和光增益现象.将该模型应用于具体器件,实验测得饱和临界偏压约6 V,稳态电流6×10-8A,响应率0.085 7 A/W,与理论计算较吻合.     

长波双色Al_xGa_(1-x)As/GaAs量子阱红外探测器的研制

介绍了长波双色AlxGa1-xAs/GaAs多量子阱红外探测器单元的设计、制作和测试。器件光敏面面积为300μm×300μm,光吸收峰值波长分别为10.8、11.6μm;采用垂直入射光耦合的工作模式,65K温度2V偏压下,两个多量子阱区的暗电流分别为4.23×10-6、4.19×10-6A;黑体探测率分别为1.5×109、6.7×109cm.Hz1/2/W;响应率分别为0.063、0.282A/W。GaAs基量子阱红外探测器(QWIP)材料生长和加工工艺成熟、大面积均匀性好、成本低、不同波段之间的光学串音小,使得AlGaAs/GaAsQWIP在制作多色大面阵方面具有明显的优势。     

基于InAs/GaAs量子点-石墨烯复合结构的肖特基光电探测器研究

石墨烯具有电子迁移率高、透过率高(T≈97.7%)且费米能级可调的特性。砷化镓的电子迁移率比硅的大5到6倍。引入砷化铟量子点后,光电探测器具有低暗电流、高工作温度、高响应率和探测率的特点,因而可被用于制备响应快、量子效率高和光谱宽的光电探测器。对基于InAs/GaAs量子点-石墨烯复合结构的肖特基结的I-V特性和光电响应进行了研究。结果表明,在0 V偏压下,该器件在400 nm～950 nm均有响应,峰值响应率可达0.18 A/W;在反向偏压下,器件的峰值响应率可达到0.45 A/W。通过对暗电流随温度变化的特性进行分析,得到了InAs/GaAs量子点-石墨烯肖特基结在室温附近以及80 K附近的势垒高度。     

近表面加工技术制备的高性能Ge:B 阻挡杂质带探测器

阻挡杂质带（BIB）探测器是当前远红外天文探测领域的主流探测器。通过近表面加工技术成功制备出了高性能的Ge:B BIB探测器,响应波数范围从50 cm^-1到400 cm^-1。在3.5 K温度和30 mV工作电压下,器件在峰值响应84.9 cm^-1处的响应率达到21.46 A·W^-1,探测率达到4.34×10¹⁴cm·Hz^1/2·W^-1。研究了BIB探测器中界面势垒对响应光谱的影响。提出了一种新的激发模式—电极区内的载流子可以通过光激发的方式越过势垒。此外,还发现了一种增强BIB探测器在小波数处相对响应强度的方法。     

掺铟硅红外探测器的特性

由于使用了硅工艺,使对在中红外区(3～5微米)工作之非本征硅掺杂红外探测器的兴趣正与日俱增。在高于77K温度下工作的Si:In光-离子化横截面是以前测定的,本文介绍在两种背景光子通量密度及探测器偏压条件下,温度从4～70K的信噪比数据。这些数据是从掺铟2.7×10~(17)/厘米~3的样品得到的。测出量子效率约50％。作为温度函数之探测度D~*,在55K约降低10％,在70K时将降到更低。迁移率及测得的响应率数据用来确定空穴寿命,发现寿命随温度的升高而增大。文献[1]提出了深杂质能级的光谱响应模型。测得的光谱响应数据与理论预测很吻合。     

GaInAs-GaInNAs-GaInAs intermediate layer structure for longwavelength lasers

Proposes two new structures, the GaInAs-GaInNAs intermediate layer (IML) and the GaInN_xAs graded wells, which show better optical properties than the commonly used GaInNAs-GaAs rectangular quantum-wells. A 1240-nm emitting IML laser has been achieved with a low-threshold current density (200 A/cm²/well) and a relatively high characteristic temperature (T_o=100 K). The IML structure is very promising for long wavelength GaAs-based laser applications     

Dynamic I-V characteristics of anAlGaAs/GaAs-based optothyristor for pulsed power-switching applications

A high-performance MBE-grown AlGaAs/GaAs-based heterostructure optothyristor has been fabricated and characterized for high-power pulsed switching applications. An LEC undoped semi-insulating GaAs of 650 μm in thickness was used as the voltage blocking layer and low-temperature GaAs grown at 200°C was used to passivate the surface and to reduce the surface leakage current. The dynamic current-voltage characteristics have been measured up to 115 A and 1974 V, which corresponds to a field intensity of more than 30 kV/cm. The dissipated energy per switching as a function of device voltage has also been determined to be in the range of 2 mJ or lower     

Improved CW operation of GaAs-based QC lasers: T/sub max/= 150 K

We present a substantial improvement in the CW performance of GaAs-based quantum cascade lasers with operation up to 150 K. This has been achieved through suitable changes in device processing of a well-characterized laser. The technology optimizes the current injection in the laser by reducing the size of the active stripe whilst maintaining a strong coupling of the optical mode to preserve low current densities. The reduction of total dissipated power is critical for these lasers to operate CW. At 77 K, the maximum CW optical power is 80 mW, threshold current is 470 mA, slope efficiency is 141 mW/A, and lasing wavelength /spl lambda//spl sim/10.3 /spl mu/m.     

Room temperature operation of a quantum-dot flash memory

A flash-memory device has been fabricated and demonstrated at room temperature by coupling a self-aligned, sub-50-nm quantum dot to the channel of a transistor on a silicon-on-insulator (SOI) substrate. Large threshold voltage shifts of up to 0.75 V are obtained for small erase/write voltages (13 V) at room temperature. At 90 K, evidence of single electron storage is observed. The small size of this device is attractive for achieving high packing densities, while the relatively large output current (100 nA-μA's), low off-state current (10 pA), and simple fabrication, requiring only minor variations in standard processing, make it suitable for integration with current silicon memory and logic technology     

Optimised device processing for continuous-wave operation in GaAs-based quantum cascade lasers

A significant improvement in the maximum continuous-wave operating temperature of GaAs-based quantum cascade lasers, T/sub max/=140 K, is reported. This has been achieved through optimised device processing that significantly reduces the total power consumption of the device and hence its self-heating.     

高功率高可靠性9XX nm激光二极管

为了提高半导体激光二极管的输出功率和可靠性,通过在有源区两侧势垒层和波导层之间引入高禁带宽度的GaAsP,抑制有源区载流子的泄漏,极大地改善了器件的性能。研究结果表明:在10~40℃温度范围内器件特征温度从原来的150 K提高至197.37 K(-75.76℃),峰值波长随温度的漂移系数为0.207 nm/℃;条宽200μm、腔长2000μm的9XX nm激光二极管可靠性工作的最大输出功率高达14.4 W;器件在注入电流为7 A时取得71.8%的最大电光转换效率,斜率效率为1.21 W/A。器件在恒定电流下的加速老化测试显示激光二极管可靠性工作寿命达2000 h以上。     

A resonant tunneling quantum-dot infrared photodetector

A novel device-resonant tunneling quantum-dot infrared photodetector-has been investigated theoretically and experimentally. In this device, the transport of dark current and photocurrent are separated by the incorporation of a double barrier resonant tunnel heterostructure with each quantum-dot layer of the device. The devices with In/sub 0.4/Ga/sub 0.6/As-GaAs quantum dots are grown by molecular beam epitaxy. We have characterized devices designed for /spl sim/6 /spl mu/m response, and the devices also exhibit a strong photoresponse peak at /spl sim/17 /spl mu/m at 300 K due to transitions from the dot excited states. The dark currents in the tunnel devices are almost two orders of magnitude smaller than those in conventional devices. Measured values of J/sub dark/ are 1.6/spl times/10/sup -8/ A/cm/sup 2/ at 80 K and 1.55 A/cm/sup 2/ at 300 K for 1-V applied bias. Measured values of peak responsivity and specific detectivity D/sup */ are 0.063 A/W and 2.4/spl times/10/sup 10/ cm/spl middot/Hz/sup 1/2//W, respectively, under a bias of 2 V, at 80 K for the 6-/spl mu/m response. For the 17-/spl mu/m response, the measured values of peak responsivity and detectivity at 300 K are 0.032 A/W and 8.6/spl times/10/sup 6/ cm/spl middot/Hz/sup 1/2//W under 1 V bias.     

大面积锗光电接收器的特性测量

本文介绍了大面积锗光电接收器的光谱响应、量子效率、频率特性和I-V特性的测量方法。在波长为1.3m处,响应度为0.47 A/W,量子效率为45％,频率响应为100kHz。在反向偏压为 5V,温度为12℃时,反向漏电流(以电流密度表示)为 2310-6A/cm2(直径为 7.5mm)。在1060℃变温范围内,测定了接收器的I-V温度特性和暗电流与温度的关系。最后对测试系统和实验现象进行了初步讨论。     

A new process of fabricating inverted-staggered tri-layer thin-filmtransistors

A new method of fabricating a-Si:H TFT with etching-stop structure has been proposed. Only one plasma-enhanced chemical vapor deposition is required in this new method and a PH₃/H₂ plasma treatment during the deposition has been used to form the TFT contact and thus saved another plasma deposition. With this method, a TFT of 500 Å active layer has been fabricated successfully. The drain current and saturation mobility of this device is 2.4×10^-7 A and 0.1 cm²/V sec, respectively, which is comparable to the conventional fabricating method. The plasma treatment will also form an additional leakage path on the TFT top surface and increase the TFT subthreshold slope. However, a current of less than 1 pA at V_G=-2.4 V can still be obtained. The possible mechanism of the contact formation by the plasma treatment is also discussed     

Preparation of thin-film transistors with chemical bath depositedCdSe and CdS thin films

The authors have fabricated the thin-film transistor (TFT) with CdSe and CdS semiconductor thin films, prepared by a low temperature chemical bath deposition (CBD) method, as an active layer. The ON-current values of the CdSe-TFTs and CdS-TFTs at a gate bias of 10 V and a source-drain voltage of 10 V are about 100 μA and 5 μA, respectively. The OFF-current values of the CdSe-TFTs and CdS-TFTs at the source-drain voltage of 10 V are less than 10 pA. The fabricated CdSe-TFTs exhibited a field effect mobility of 15 cm²/V-s, threshold voltage of 3.5 V, subthreshold slope of 0.5 V/dec., and ON/OFF current ratios exceed 10⁷. A field effect mobility of I cm ²/V-s, a threshold voltage of 2.6 V, a subthreshold slope of 0.6 V/dec., and an ON/OFF current ratios exceed 10⁶ were observed for CdS TFTs