新型三腔谐振腔增强型光探测器的理论分析和数值模拟

提出了一种新的谐振腔增强型 (RCE)光探测器结构 ,它将器件结构中的谐振腔分为三个子腔。分析表明 ,采用这种新结构的光探测器在保留了 RCE光探测器优点的同时 ,还实现了器件量子效率及其光谱响应线宽之间制约关系的解耦 ,因而可以同时获得窄的光谱响应线宽 (<1 nm) ,高的量子效率 (>90 % )和高的响应速度。该器件可望在密集波分复用 (DWDM)光通信系统中得到广泛应用     

窄线宽和高量子效率的光探测器

共振腔增强光探测器已成为有关波分复用(WDM)近期研究的焦点,但它们也有某些限制。像普通光探测器一样,响应速度和量子效率之间不存在妥协,在光谱响应线宽和量子效率之间存在妥协。量子效率超过50%的探测器的光谱响应线宽宽于20 nm,使该种光探测器不能用于波分复用应用。现在北京邮电大学做成一个具有滤波、间隔器和吸收子腔的波长选择光探测器,它能同时提供窄线宽和高量子效率。在理想的条件下这些科学家相信光谱响应线宽能小于1 nm,量子效率可以高达90%。在实际条件下,该光探测器有一过得去的3 nm模失匹范围,而且与其间隔器腔的最佳厚度有近似100 nm可以接受的变化范围。其过滤腔损失在某种程度上能得到补偿。在实验中获得近似0.97 nm的光谱响应线宽和超过50%的外部量子效率。     

GaAs/GaInNAs多量子阱谐振腔增强型长波长光探测器

报道了一种具有高速响应特性的GaAs基长波长谐振强增强型(RCE)光探测器,它采用分子束外延技术(MBE)在GaAs衬底上直接生长GaAs/AlAs布拉格反射镜(DBR)和GaInNAs/GaAs多量子阱吸收层而形成,解决了GaAs系材料只能对短波长光响应的问题,实现了GaAs基探测器对长波长光的响应。该器件在峰值响应波长1296.5nm处获得了17.4%的量子效率,响应谱线半宽为11nm,零偏置时的暗电流密度8.74×10-15A/μm2,具有良好的暗电流特性。通过RC常数测量计算得到器件的3dB带宽为4.82GHz。     

1.3 μm InGaNAs/GaAs多量子阱"一镜斜置三镜腔"光探测器

报道了一种基于InGaNAs/CmAs多量子阱的1.3μm GaAs基"一镜斜置三镜腔"光探测器,采用分子束外延(MBE)技术在GaAs衬底上直接生长高质量的GaAl/AIAs分布布拉格反射镜(DBR)和InOaNAs/GaAs多量子阱吸收层,实现了单片集成的GaAs基长波长"一镜斜置三镜腔"光探测器.探测器的峰值响应波长位于1298.4 nm,光谱响应线宽(FWHM)为1.0 nm,量子效率为3%,在零偏压下其暗电流密度为3.75×10 13A/μm2.     

一种具有平顶陡边响应的长波长光探测器

在PIN型光探测器的基础上制备了一种适用于波分复用系统的具有平顶陡边响应的长波长光探测器。利用低压金属有机化学气相沉积(LP-MOCVD)设备在GaAs衬底上二次外延生长了具有台阶结构的GaAs/AlGaAs滤波腔和InP基PIN光探测器。高质量的GaAs/InP异质外延采用了低温缓冲层生长工艺;具有台阶结构的Fabry-Pérot(F-P)滤波腔采用了纳米量级台阶的制备方法。通过理论计算优化了实现平顶陡边光谱响应特性的器件结构;并通过实验成功制备出了具有平顶陡边响应性能的光探测器,器件的工作波长位于1 549nm,峰值量子效率大于25%,0.5dB光谱响应线宽为3.9nm,3dB光谱响应线宽为4.2nm,响应速率达到17GHz。     

新型光电探测器的研究

针对RCE光电探测器存在的问题提出两种解决方案。将InP／空气隙的分布布拉格反射镜(DBR)结构引入RCE光探测器,只用1．5对InP／空气隙计算反射率约为95％,解决了长波长反射镜制备问题。所制备的器件,在波长1．585μm处获得了约54．5％的峰值量子效率,以及8GHz的3dB响应带宽。另一种引入斜镜结构解除了量子效率与超窄光谱响应线宽的相互制约。     

一种具有平顶陡边响应的新型谐振腔增强型(RCE)光电探测器的理论分析及模拟

提出了一种适用于波分复用系统的具有平顶陡边响应的新型谐振腔增强型 (RCE)光电探测器结构 ,模拟得到了量子效率从峰值下降 0 5dB的线宽 1 8nm ,10dB的线宽 5 6nm ,2 0dB的线宽 10 4nm ,量子效率峰值99 7%,几乎没有凹陷的响应曲线。     

高性能InP基谐振腔增强型长波长光探测器

介绍了目前实现高性能InP基谐振腔型(RCE)长波长光探测器的几种方案。采用InP 空气隙DBR结构、正入射光、响应波长为1550nm的高灵敏度、高速InP基长波长RCE光探测器,在1510nm波长处获得了59%的量子效率,在器件台面面积仍很大的情况下(50μm×50μm),获得了8GHz的3dB响应带宽。     

新型的波长选择波导光电探测器的研究

提出了一种新型的具有波长选择性的波导型(WG)光电探测器(PDs)与即谐振波腔选频斜镜耦合包芯波导(RICEWG)。对其工作原理进行了详细的理论分析和数值模拟,提出了优化设计方案,讨论了实现方法。结果表明,这种结构具有使量子效率与响应带宽和光谱响应线宽同时解耦的优点;可以获得<1nm的光谱响应线宽同时保持>80%的量子效率,并且可以分别优化光谱响应线宽和量子效率。     

具有多波长处理功能的单片集成光探测器阵列

从理论上设计并研制了一种用于可重构光分插复用技术中的具有多波长处理功能的单片集成光探测器阵列,器件在GaAs基衬底上集成了GaAs/AlGaAs材料的法布里一珀罗谐振腔和InP-In0.53 Ga0.47 As-InP材料的PIN光探测器.为了能够实现对多路波长的探测,首先利用湿法腐蚀,改变不同区域谐振腔的厚度,然后通过二次外延完成谐振腔的生长,最后利用低温缓冲层技术在GaAs材料上异质外延高质量的InP基的PIN结构.器件的工作波长位于1500 nm左右,可实现对4路波长,间隔为10 nm的光信号探测,光谱响应线宽低于0.8 nm,峰值量子效率达到12%以上,响应速率达到8.2 GHz.实验测试结果与理论分析进行了对比,并得到了很好的解释.     

Monothically Integrated Long-Wavelength Tunable Photodetector

This paper demonstrated a tunable long-wavelength photodetector by using the heteroepitaxy growth of InP-In_0.53Ga_0.47As-InP p-i-n structure on a GaAs-based GaAs/AlAs Fabry-Perot filter structure. High-quality heteroepitaxy was realized by employing a thin low-temperature buffer layer. A wavelength tuning range of 10.0 nm, an external quantum efficiency of about 23%, a spectral linewidth of 0.8 nm, and a 3-dB bandwidth of 6.2 GHz were simultaneously obtained in the device.     

基于低温缓冲层的单片集成长波长可调谐光探测器

实现了一种单片集成的长波长可调谐光探测器.通过外延实验,摸索出低温缓冲层的最佳生长条件,成功地在GaAs衬底上生长出晶格失配度约4%的高质量的InP基材料.基于此低温缓冲层,在GaAs衬底上首先生长GaAs/AlAs材料的F-P腔滤波器,然后异质外延InP-In0.53 Ga0.47 As-InP材料的PIN结构.制作出的器件通过热调谐,峰值波长从1533.1nm红移到1543.1nm,实现了10.0nm的调谐范围,同时响应线宽维持在0.8nm以下,量子效率保持在23%以上,响应速率达到6.2GHz.     

Monolithically Integrated Photodetector Array With a Multistep Cavity for Multiwavelength Receiving Applications

A monolithically integrated photodetector array used for multiwavelength receiving was realized by growth of an InP-In_0.53Ga_0.47As-InP p-i-n structure on a GaAs/AlGaAs Fabry-Perot filter. The filter with a multistep cavity was fabricated by wet etching and regrowth. Each photodetector in the array detects a different wavelength, so the array functions as a multiwavelength receiver. The high-quality GaAs/InP heteroepitaxy was realized by employing a thin low temperature buffer layer. The photodetector array detects four wavelength channels, whose interval is about 10 nm , around 1550 nm. A full-width half-maximum less than 0.5 nm , a peak quantum efficiency over 15%, and a 3-dB bandwidth of 9 GHz were simultaneously obtained in the photo-detector array.     

基于异变缓冲层与应变层超晶格的InP/GaAs异质外延

利用低压金属有机化学气相沉积技术, 开展InP/GaAs异质外延实验。由450 ℃生长的低温GaAs层与超薄低温InP层组成双异变缓冲层, 并进一步在正常InP外延层中插入In1-xGaxP/InP(x=7.4%)应变层超晶格。在不同低温GaAs缓冲层厚度、应变层超晶格插入位置及应变层超晶格周期数等条件下, 详细比较了InP外延层(004)晶面的X射线衍射谱, 还尝试插入双应变层超晶格。实验中, 1.2 μm和2.5 μm厚InP外延层的ω扫描曲线半峰全宽仅370 arcsec和219 arcsec; 在2.5 μm厚InP层上生长了10周期In0.53Ga0.47As/InP 多量子阱, 室温PL谱峰值波长位于1625 nm, 半峰全宽为60 meV。实验结果表明, 该异质外延方案有可能成为实现InP-GaAs单片光电子集成的一种有效途径。     

低温缓冲层对MBE生长ZnTe材料性能的改善

研究了低温缓冲层对在GaAs(001)衬底上用分子束外延(MBE)生长ZnTe薄膜晶体质量的影响。发现插入低温缓冲层后ZnTe的结晶质量、表面形貌和发光质量都得到了显著的提高,双晶X射线摇摆曲线(DCXRC)的ZnTe(004)衍射峰半峰宽(FWHM)从529 arcsec减小到421 arcsec,表面均方根(RMS)粗糙度从6.05 nm下降到3.93 nm。而作为对比,插入高温缓冲层并不能对ZnTe薄膜的质量起到改善作用。基本上实现了优化工艺的目标并为研制ZnTe基光电器件微结构材料奠定了很好的实验基础。     

用于单片集成光接收机前端的GaAs基InP/InGaAs HBT

实现了一种可用于单片集成光接收机前端的GaAs基InP/InGaAs HBT。借助超薄低温InP缓冲层在GaAs衬底上生长出了高质量的InP外延层。在此基础上,只利用超薄低温InP缓冲层技术就在半绝缘GaAs衬底上成功制备出了InP/InGaAsHBT,器件的电流截止频率达到4.4GHz,开启电压0.4V,反向击穿电压大于4V,直流放大倍数约为20。该HBT器件和GaAs基长波长、可调谐InP光探测器单片集成为实现适用于WDM光纤通信系统的高性能、集成化光接收机前端提供了一种新的解决方法。     

GaAs/Si异质外延的新进展

本工作从原理和实验技术上证实了氯化物VPE技术可用于CaAs/Si异质外延.CaAs/Si外延层表面平整光亮.对外延层进行了组分测量、高分辨率电镜和X-射线衍射分析.结果表明,外延层是符合化学计量比的CaAs单晶,外延层浓度可控范围为10~(14)～10~(17)cm~(-3),纵向掺杂分布平坦.用这种材料制成MESFET样管,跨导为40mS/mm.     

Interface structure and growth mode of quantum wire and quantum dot GaAs-AlAs structures on corrugated (311)A surfaces

GaAs-AlAs corrugated superlattices (CSL) are formed on spontaneously nanofaceted (311)A surfaces. Using high-resolution transmission electron microscopy (HRTEM) along the $[\bar 233]$ zone axis with an appropriate image evaluation technique to enhance the contract between GaAs and AlAs we found two distinct lateral periodicities along the $[0\bar 11]$ directions for two different CSL layer thickness regimes. For multilayer deposition with GaAs layer thickness exceeding 1 nm the lateral periodicity of 3.2 nm is clearly revealed. The contrast originates from the thickness modulation of both AlAs and GaAs layers with a period of 3.2 nm in the $[0\bar 11]$ direction. The corrugation height is about 1 nm and it is symmetric for both upper and lower GaAs-AlAs interfaces. Thicker sections of the thickness-modulated AlAs and GaAs layers of the CSL are shifted by a half period with respect to each other. In the regime when the GaAs deposited average thickness is below 1 nm, which is necessary for complete coverage of the AlAs surface, a lateral periodicity of ≈1.5–2 nm is additionally revealed. We attribute this effect to the formation of local GaAs clusters dispersed on a corrugated (311)A AlAs surface resulting in a local phase reversal of the AlAs surface in their vicinity upon subsequent overgrowth. This reversal can be explained by the same effect as the phase shift of the surface corrugation upon heteroepitaxy on (311)A. In our model AlAs does not wet the GaAs cluster surface, unless different more energetically favorable scenario is possible. This causes accumulation of AlAs in the vicinity of the GaAs cluster and, as a result, the local phase reversal of the AlAs surface. The AlAs corrugated surface domains with different phases coexist on the surface resulting in an additional periodicity revealed in the HREM contrast modulation. Additionally HRTEM studies indicate that the AlAs-GaAs interface inclination angles in both regimes are 40° and 140° with respect to the flat (311) surface in an argreement with the {331} facet geometry model proposed by R. Nötzel, N.N. Ledentsov, L. Däweritz, M. Hohenstein, and K. Ploog.     

Low temperature cleaning of Si by a H2/AsH3 plasma prior to heteroepitaxial growth of GaAs by metalorganic chemical vapor deposition (MOCVD)

A method using a H₂/AsH₃ plasma to clean the Si surface before GaAs heteroepitaxy was investigated and the dependence of the effectiveness of this treatment on arsine partial pressure was studied. Thin GaAs-on-Si films deposited on the plasma-cleaned Si were analyzed using plan-view TEM, HRXTEM and SIMS. Although not optimized, this method of Si cleaning makes heteroepitaxial deposition of GaAs possible. Some roughening of the Si surface was observed and a possible explanation is offered. Using the results of this study, thick (2.5–3.0μm) epitaxial GaAs films were then deposited and their quality was evaluated using RBS, XTEM and optical Nomarski observation. All Si surface cleaning and GaAs deposition were carried out at temperatures at or below 650°.