集成光电子学国家重点实验室知识库

在信息产业、生物医学等科技领域越来越受关注的今天，新型光电子、光通信科技必将以更快的速度发展。Si基光电子集成采用成熟价廉的微电子加工工艺，将光学器件与多种功能的微电子电路集成，是实现光通信普及发展和光互连的有效途径。Si基光电探测器是Si基光通信系统的关键器件之一。随着近年来Si基Ge材料外延技术的突破性进展，Si基Ge光电探测器因为兼顾了Si基光电子集成和对光通讯波段(1.31和1.55μm)的高效探测，成为了当今研究的一大热点。
    半导体光电探测器的性能与其结构密切相关。PIN型光电探测器是最常见的探测器，可以普遍应用于光通讯光互连系统；雪崩光电二极管(APD)因为具有较高的响应度和内部增益，在实现单光子探测方面具备很大的优越性，适用于当今迅猛发展的生物光子学和量子信息学；共振腔增强型的光电探测器(RCE-PD)，集波长选择器、高速光信号接收器于一体，而且具备共振增强作用、高饱和功率输出等特点，是局域网、光纤入户和现代波分复用(Wavelength-Division Multiplexing,WDM)系统光通信网络的一种优选方案；波导结构探测器(Waveguide-PD)可以解除探测器的响应带宽和量子效率之间的矛盾，而且其结构特点更易于实现与调制器等光波导器件的集成，是片上光互连的首选探测器。
    本论文围绕高性能Si基Ge光电探测器这一研究目标，开展了多种结构的光电探测器的研制，包括PIN型PD的研制及其优化、吸收区与倍增区分离结构(SACM)的Ge-on-Si APD、RCE-PD和Waveguide-PD，主要研究结果如下：

1.                成功研制了PIN型Ge-on-Si光电探测器，器件在-1V外加偏压下暗电流密度为46.6mA/cm2，在1.31μm和1.55μm波长下器件的量子效率分别为40%和17%；然后改进了实验方法，在制作器件之前将Ge-on-Si材料在850℃条件下快速退火1分钟，从而改善材料质量，器件的暗电流密度降低至4mA/cm2，这是目前国际上报道的最好结果之一。

2.                研制出了PIN型Ge-on-SOI光电探测器，在1.31μm和1.55μm波长的量子效率分别为62%和25%。在-3V外加偏压下，器件的3dB带宽为12.6GHz。25μm直径器件，3dB带宽更是达到了13.4GHz。同时，制作了均匀性很好的1×4探测器阵列，单个器件的3dB带宽达13.3GHz。

3.                在国际上首次研究了硅基锗光电探测器的高饱和特性。在-1V和-2V外加偏压下，探测器的1-dB小信号压缩电流分别为22mA和40mA,相应的光功率分别为67.5mW和110.5mW。

4.                成功研制了吸收区和倍增区分离的Si基Ge雪崩光电二极管，器件的穿通电压Vpt约为29V，击穿电压Vbd(暗电流等于100μA时的电压)为39.5V。在击穿电压附近，如39V时，SACM-Ge-on-Si APD的增益为40。

5.                解决了背面ICP深刻蚀工艺难题，成功制备了中心波长在1.55μm，量子效应高达62%的共振腔增强型Si基Ge光电探测器。

Optoelectronics and optical communication technology has developed rapidly as the information industry and bio-medical technology becoming increasingly important. Silicon-based optoelectronic integrated technology is low-cost but effective on achieving popularization and development of optical communication. Silicon-based photodetector is one of the key devices of optical communication system. The Ge-on-Si photodetector has breakthrough progress recently and become the research focus, because it can response to 1.31μm and 1.55μm well.
   The performance of the semiconductor photodetector is closely related to its structure. PIN photodetector is the most common for applying to optical communication and interconnection. APDs often apply to bio-photonics and quantum information science due to their advantages of high responsivity and internal gain on single-photon detection. RCE-PD with resonance enhancement and high saturation power output characteristics sets wavelength selector and high-speed optical receivers in one, so it’s a preferred solution to local area networks, home fiber and the modern WDM optical communication network. Whereas, waveguide-PD can solve the contradiction between the response bandwidth and quantum efficiency as well as integrate with optical fibers, waveguides and modulators easily.
     In this thesis, various structures have been research for achieving highperformance Si-based Ge photodetectors.The work covered the development and optimization of PIN-PD, SACM-Ge-on-Si APD, RCE-PD and waveguide-PD. The main results described as follows.

1.                A PIN Ge-on-Si photodetector successfully developed.The dark current density of the device was 46.6mA/cm2 at -1V bias voltage. The quantum efficiency was 40% and 17% at 1.31μm and 1.55μm ; RTA was proposed to decrease the dark current of the Ge-on-Si photodetector.The as-grown Ge-on-Si materials were annealed at 850℃ for 1 minute to reduce the dislocation density.The dark current density of device was 4mA/cm2 at -1V bias voltage,which was the one of best reported results around the world.

2.                A PIN Ge-on-SOI photodetector was achived successfully. The corresponding quantum efficiency was 62% and 25% at 1.31μm and 1.55μm,respectively. The 3dB bandwidths of the 30-μm-diameter device was 12.6GHz at reversebias values of 3V.Especially,the 3dB bandwidth of 25-μm-diameter device was 13.4GHz at 1.55μm.At the same time,1×4 Ge-on-SOI PIN photodetector arrays were achived.The four devices in the same array show a good consistency. At the reverse bias of 3V, the bandwidth of the single device was about 13.3GHz.

3.                The high saturation power characteristics of Ge-on-Si photodetector was reported for the first time. The 1-dB small-signal compression optical currents were 22mA and 40mA of the 70-μm-diameter device,and the corresponding optical power values were 67.5mW and 110.5mW at reverse-bias of 1 and 2V.

4.                Separate Absorption, Charge and Multiplication(SACM) Si-based Ge Avalanche photodetector has been achieved. Its punchthrough voltage was about 29V, breakthrough voltage was 39.5V. The APD exhibited a gain of 40 at 1.31μm and 39V.

5.                Using ICP back deep etching technology,the Resonant Cavity Enhanced(RCE) Ge-on-Si photodector was fabricated with a quantum efficiency of 62% at center wavelength of 1.55μm.

6.                A lateral waveguide structure Ge-on-SOI photodetector has been designed. Some results of theoretical modeling was described in this thesis.