Fabrication of Semiconductor Quantum-wire and Quantum-box Structures with Bi-axial Strain and Their Applications to Photonic Devices

为了实现用于光通信的长波长半导体激光器的极低电流和高效率工作，我们研究了双轴应变量子线和量子盒结构的低损伤制造工艺。本文的研究结果总结如下：1)采用电子束光刻和两步有机金属气相外延生长制备了1.5μm波长GaInAsP/InP压缩应变量子线激光器。采用CH_4/H_2混合气体反应刻蚀（RIE）技术，首次实现了线宽为21nm、波长为100nm的双层堆叠量子线激光器。2)为了减少由于应变松弛导致的刻蚀/再生界面处的非辐射复合中心，采用应变补偿多量子阱（MQW）结构作为初始晶圆，实现了由多个（5层）线状有源区堆叠组成的激光器（线宽为43n…在100nm周期内多m）。结果，在室温下获得的阈值电流密度低至318A/cm^2，几乎是初始晶圆获得的MQW激光器的60%。在高达85℃的温度下，不仅获得了低阈值电流密度操作，而且获得了高差分量子效率操作。这一事实清楚地表明，本研究采用的制造工艺是一种极有希望的低损伤超细结构实现方法。3)利用我们的新方法，我们实现了一种由周期性排列的双层线状有源区组成的新型分布式反馈（DFB）激光器。结果表明，在1.55μm波长下，器件的阈值电流密度为94A/cm^2 （20μm宽条纹），阈值电流为0.7mA （2.3μm宽BH条纹），差分量子效率为23%/facet。此外，还首次阐明了驻波剖面与活跃区位置的匹配所带来的优越单模性。少

In this work, in order to realize extremely low current and high efficiency operation of long-wavelength semiconductor lasers for optical communications, we have investigated low-damage fabrication process of bi-axially strained quantum wire and quantum-box structures.Results obtained in this research are summarized as follows.1) 1.5μm-wavelength GaInAsP/InP compressively strained quantum-wire lasers were fabricated by electron beam lithography, and 2-step organic metal vapor phase epitaxy growth. Double layered stacked quantum-wire lasers with the wire width of 21nm in the period of 100nm were realized for the first time by adopting reactive-ion-etching (RIE) with CH_4/H_2 gas mixture.2) In order to reduce non-radiative recombination centers at the etched/regrown interfaces due to a strain relaxation, strain compensated multiple-quantum-well (MQW) structure was used as an initial wafer and lasers consisting of stacked multiple (5 layered) wirelike active regions (the wire width of 43n … More m in the period of 100nm) were realized. As the result, threshold current density as low as 318A/cm^2, which is almost 60% of MQW lasers obtained from the initial wafer, was obtained at room temperature. Not only a low threshold current density operation but also high differential quantum efficiency operation were obtained up to 85℃. This fact clearly indicates that the fabrication process employed in this research is promising as a low-damage realization method of ultra-fine structures.3) By using our newly developed method, we realized a new type of distributed feedback (DFB) lasers consisting of periodically arranged double layered wirelike active regions. As the results, a record low threshold current density of 94A/cm^2 (20μm wide stripe) and a record low threshold current of 0.7mA (2.3μm wide BH stripe) as well as differential quantum efficiency of 23%/facet were achieved at an emission wavelength of 1.55μm. Moreover, superior single-mode-properties attributed to the matching between the standing wave profile and the position of the active region were clarified for the first time. Less