基于光微机电系统集成制备波长可调氮化物激光器的基础研究

GaN-based nitride semiconductor demonstrates large potential to fabricate ultraviolet, visible and near-infrared light-emitting devices, since the bandgap of this serial semiconductors could be tuned from 0.63eV to 6.2eV, by changing the concentration of In,Ga and Al in the nitrides. Some of these devices such as GaN-based light-emitting diodes (LEDs) and laser diodes (LDs) have entered the world market.On the other hand, Optical MEMS (Micro-Electro-Mechanical-Systems) includes many kinds of devices such as tunable lasers & filters, variable optical attenuators, programmable optical add/drop multiplexers, optical switches and cross-connectors, wavelength division multiplexers, integrated optical components, dispersion compensators and so on. With the development of communication and information science and technology, optical MEMS will be widely explored. However, optical MEMS couldn't be truly integrated devices until the light source is integrated with MEMS on the same Si wafer. For example, a tunable micro-laser or tunable grating monolithically fabricated from the InGaN/GaN LED grating on the Si-MEMS actuator structure. Such kind of integration is at the beginning of research all over the world. .The distributed feedback (DFB) laser makes a stably single-mode oscillation. As the DFB laser has a superior of laser diode. It is used for various purposes. Recently, tunable laser with a wide tuning range and a single mode oscillation is needed for miniaturization, simplification and integration of several optical systems..The fabrication of a tunable laser with a wide tuning range and a single mode oscillation could be realized by using GaN series semiconductor and Si-MEMS technology. For the realization of the tunable laser, we proposed a new structure. It consists of a self-supported subwavelength nitride grating with gain. The period of the grating is changed by an nitride electro static comb actuator.GaN series semiconductor was etched by the chlorine plasma.HfO2 mask is to be used as etching mask. In addition, it worked as a electric insulating layer and a layer to compensate the deflection of self-supported nitride grating and actuator. Some other research contents also will be studied, including the design of the nitride actuator and nitride grating based on the theory of static micro-actuator and the analysis of electromagnetic field analytical and finite difference time domain method. Also, the evaluation of the nitride actuator and grating will be carried out with the current/voltage measurement, laser measuring instrument, photoluminescence, micro-photoluminescence, reflectance spectrum and spectrum analyzer. Furthermore,some fundermental issues such as the etching mechanism of Cl2 plasma on the deep etching of GaN and the obtain of smooth vertical surface of GaN-based semiconductor will be studied.

氮化物半导体与硅基光微机电系统集成制备新型光电子器件与光微系统是符合信息产业发展的国际前沿研究领域。本项目开展自支撑氮化物微驱动器和氮化物共振光栅集成制备波长可调激光器的基础研究。项目的主要创新点为(1)利用悬空的自支撑氮化物半导体共振光栅实现激光的增益放大,(2)结合硅基光微机电系统技术和微加工技术实现氮化物共振光栅的周期可调，从而实现激光的波长可调,(3)共振光栅的空间间距变化由氮化物材料自身的微驱动器提供可执行功能。我们计划利用在氮化物薄膜表面沉积HfO2薄膜以缓和光栅结构与微驱动器由于残余应力而形成的弯曲问题以及采取硬SOG作为掩模板减少氮化物薄膜的深刻蚀过程中刻蚀离子对薄膜垂直表面的损伤。最终使得单片集成的具有平整表面的波长可调氮化物激光器成为可用的新型光电子器件。同时探索解决氮化物微机电系统研制过程中的基础科学问题，如氮化物半导体体加工与表面加工的机理与模式等。

氮化物半导体与硅基光微机电系统集成制备新型光电子器件与光微系统是符合信息产业发展的国际前沿研究领域。本项目开展了自支撑氮化物微驱动器和氮化物谐振光子光栅集成制备波长可调激光器的基础研究。结合耦合波理论及介质平板波导理论计算硅基氮化物光子光栅、硅基氮化物微驱动器、SOI基氮化物光子光栅、SOI基氮化物微驱动器、硅基氮化物光栅滤波器的关键结构参数，利用基于有限元理论软件COMSOL对这些结构和器件建立二维和三维仿真模型，探讨了不同光栅高度、光栅宽度及光栅周期对激光谐振峰的影响；探讨了梳齿间隔、梳齿个数、梳齿长宽、支撑梁长宽等对驱动器驱动性能的影响并进行了仿真优化。利用微纳加工工艺加工了几个相关的器件，如硅基氮化镓集成可调光栅角度滤波器、硅基氮化镓集成跟踪聚焦微镜、和SOI基GaN微驱动器、硅基氮化镓自支撑悬臂梁以及硅基GaN发光器和纳米柱发光器件。利用MBE工艺，采用AlN/GaN多层超晶格和晶化HfO2作为缓冲层，在硅基板、SOI基板上生长了高质量的层状和纳米柱状的InGaN/GaN量子阱、p-i-n结构薄膜，并制备成高效发光的LED。为了缓和硅基氮化物微纳加工过程中的产生的应力，采用晶化HfO2作为缓冲层，探讨了平滑硅基氮化物半导体的微纳加工机理。为了进一步提高硅基微驱动器的低电压和大位移的驱动性能，本项目组成员还在硅基上生长铁电压电薄膜，并测试其性能。为以后的硅基压电驱动器驱动化合物半导体光子器件打下了坚实的基础。到目前为止，发表或接收期刊论文27篇，会议论文3篇，其中SCI收录论文13篇，EI收录论文10篇。申请专利8项，其中授权专利2项。