CMOS兼容近红外Si0.7Ge0.3/Si p-i-n(SOI)光电探测器

报道了一种采用UHV/CVD锗硅工艺和CMOS工艺流程在SOI衬底上制作的横向叉指状Si0.7Ge0.3/Si p-i-n光电探测器.测试结果表明:其工作波长范围为0.7～1.1μm,在峰值响应波长为0.93μm,响应度为0.38A/W.在3.0V的偏压下,其暗电流小于1nA,寄生电容小于1.0pF,上升时间为2.5ns.其良好的光电特性以及与CMOS工艺的兼容性,为研制能有效工作于近红外光的高速、低工作电压硅基光电集成器件提供了一种新的尝试,在高速光信号探测等应用中有一定的价值.     

SiGe HBT基区结构的优化对欧拉电压的影响

欧拉电压是SiGe HBT一项重要的直流参数,受到基区结构(如Ge组分)的影响。研究发现,高温过程会导致硼的外扩散,从而影响异质结的位置,使欧拉电压受到影响。实验发现,通过优化基区结构,加厚CB结处i-SiGe厚度,可获得VA=520 V,βVA=164,320 V的SiGe HBT。     

1.55μm Si基光电探测器的研究进展

从材料的生长、器件结构的选择等方面对1．55μm锗光电探测器的研究进展进行了综述，对Ge量子点共振腔增强型光电探测器的应用前景进行了探讨与展望。     

Monolithic SiGe Up‐/Down‐Conversion Mixers with Active Baluns

The purpose of this paper is to describe the implementation of monolithically matching circuits, interface circuits, and RF core circuits to the same substrate. We designed and fabricated on‐chip 1 to 6 GHz up‐conversion and 1 to 8 GHz down‐conversion mixers using a 0.8 µm SiGe hetero‐junction bipolar transistor (HBT) process technology. To fabricate a SiGe HBT, we used a reduced pressure chemical vapor deposition (RPCVD) system to grow a base epitaxial layer, and we adopted local oxidation of silicon (LOCOS) isolation to separate the device terminals. An up‐conversion mixer was implemented on‐chip using an intermediate frequency (IF) matching circuit, local oscillator (LO)/radio frequency (RF) wideband matching circuits, LO/IF input balun circuits, and an RF output balun circuit. The measured results of the fabricated up‐conversion mixer show a positive power conversion gain from 1 to 6 GHz and a bandwidth of about 4.5 GHz. Also, the down‐conversion mixer was implemented on‐chip using LO/RF wideband matching circuits, LO/RF input balun circuits, and an IF output balun circuit. The measured results of the fabricated down‐conversion mixer show a positive power conversion gain from 1 to 8 GHz and a bandwidth of about 4.5 GHz.     

Germanium islands embedded in strained silicon quantum wells grown on patterned substrates

Germanium islands were embedded in strained silicon quantum wells in order to provide an improved electron confinement in vicinity of the islands. Growth was performed on relaxed SiGe layers. Patterned substrates were used, favouring lattice relaxation as well permitting the fabrication of small Ge islands at deposition temperatures above 500 °C. Photoluminescence analysis reveals a strongly reduced dislocation related signal. The low temperature spectra are dominated by intense signals from the germanium islands. The origin of these signals were investigated by removing the islands by etching, analysing reference samples without a silicon quantum well, varying the germanium deposition and the growth temperature.     

Energy levels in doped SiGe quantum well studied by admittance spectroscopy

SiGe/Si quantum wells (QWs) with different Boron doping concentrations were grown by molecular beam epitaxy (MBE) on p-type Si(1 0 0) substrate. The activation energies of the heavily holes in ground states of QWs, which correspond to the energy differences between the heavy hole ground states and Si valence band, were measured by admittance spectroscopy. It is found that the activation energy in a heavily doped QW increases with doping concentration, which can be understood by the band alignment changes due to the doping in the QWs. Also, it is found that the activation energy in a QW with a doping concentration of 2 × 10²⁰ cm⁻³ becomes larger after annealing at a temperature of 685 °C, which is attributed to more Boron atoms activation in the QW by annealing.     

基于紫外光刻的双轴张应变Ge/SiGe多量子阱电吸收调制器北大核心CSCD

采用紫外光刻工艺(ultraviolet lithography technique,UVL),在互补金属氧化物半导体(complementary metal oxide semiconductor,CMOS)兼容的硅基平台上制作了基于悬空微桥结构在Ge/SiGe多量子阱材料中引入双轴张应变的低偏振相关电吸收调制器。利用拉曼光谱测试了器件引入双轴张应变的大小,并对器件在横电(transverse electric,TE)偏振和横磁(transverse magnetic,TM)偏振下的光电流响应、调制消光比和高频响应等性能进行了测试。器件的低偏振相关消光比在0 V/4 V工作电压下可达5.8 dB,3 dB调制带宽在4 V反向偏置电压时为8.3 GHz。与电子束光刻工艺(electron beam lithography technique,EBL)相比,采用UVL制作的器件在调制消光比、高频响应带宽等性能上略差一点,但具有曝光时间短、成本低和可大批量生产等优势,应用前景广阔。     

Analytical,structural and electrical characterization of SiGe layers by electron microbeam techniques

k-ratios of Ge-L and Si-K measured at different beam energies allow to evaluate simultaneously composition and thickness of SiGe layers on a Si substrate. A simple technique applying backscattered electrons also enables estimation of composition of bulk SiGe and of composition and thickness of relatively thick (200 nm) SiGe layers on Si. Electron channeling patterns of pseudomorphic SiGe/Si structures and of pure Si substrate show no significant differences whereas in relaxed structures a smearing of the pattern with increasing density of misfit dislocations is observed. Under particular conditions the technique of the electron beam induced current permits imaging of recombination-active misfit dislocations with a spatial resolution around 0.2 m. Moreover, a repulsion of holes due to the valence-band offset in a n-Si/SiGe heterostructure was detected.     

太赫兹Si/SiGe量子级联激光器的能带设计

使用nextnano3模拟软件计算Si/Si1-xGex/Si量子阱的能带结构,对Si/SiGe量子级联激光器有源区的能带结构进行设计,结果表明使用Ge组分为0.27～0.3,量子阱宽度为3nm的SiGe合金与垒宽为3nm的Si层构成对称应变级联异质结构,有利于优化THz Si/SiGe量子级联激光器结构.     

高频大功率SiGe/Si HBT的设计

详细地阐述了高频大功率SiGe/Si异质结双极晶体管(HBT)设计中的一些主要问题,主要包括器件的纵向设计中发射区、基区以及收集区中掺杂浓度、形貌分布、层厚的选择以及横向布局设计中的条宽、间隔的选择等.并对这些主要参数的选择给出了一些实用的建议.