中国科学院半导体研究所机构知识库

2~4μm波段中红外激光器在痕量气体检测、激光医疗、空间光通信和红外光电对抗中都有着十分广泛而重要的应用价值。基于GaSb基窄带隙半导体的量子阱半导体激光器以其小体积、高功率、高效率和良好的环境适应性等突出优势成为中红外波段高性能激光器技术研究的核心体系。近年来，拓展GaSb基量子阱激光器激射波段是该体系具有挑战性的前沿研究课题。在科技部973计划、国家自然科学基金委重点项目等的支持下，本文研究了高性能GaSb基I型量子阱激光器，开展了激光器材料的分子束外延生长、器件设计和制备工艺研究，此外还探索了分布布拉格反射(DBR)高阶模式激光器的设计和制备工艺技术。取得阶段性成果如下：

（1）基于GaSb体系二元材料参数采用线性插值法Vegard’s法则计算了InGaAsSb和AlGaAsSb的晶格常数，得到了不同III族组分下的As组分，并进一步计算了AlGaInAsSb五元材料的晶格常数。采用Sadao-Adachi近似模型计算了InGaAsSb和AlGaAsSb不同组分下的折射率。基于折射率参数计算出2微米和3微米光场下的光学限制因子，以及光学限制因子随限制层Al组分和波导层厚度的变化关系，结合串联电阻和开启电压选定限制层Al组分的范围（0.5~0.7）、得出了最佳波导层厚度与激射波长的相关性质。

（2）四元、五元势垒InGaAsSb量子阱的分子束外延（MBE）生长条件。基于PL谱测试对发光性能进行表征，采用HR-XRD、AFM和光学显微镜测试分析材料内部结构和表面形貌，分别得出四元势垒AlGaAsSb的优化生长温度以及合适的量子阱应变范围（1.3%），得出五元势垒AlGaInAsSb不同生长温度下的应力改变规律，发现四元、五元势垒的优化生长温度都处于再构温度Tc+45℃以上。采用优化的外延生长条件并通过引入界面控制获得了InGaAsSb/AlGaInAsSb量子阱，室温PL谱发光波长覆盖了2.7~3.4μm范围。

（3）研制成功2.6-2.9微米波段的GaSb基量子阱激光器。其中，激射波长2.6μm的激光器实现室温连续激射，输出功率325mW，阈值电流402A/cm2；激射波长2.75μm激光器实现室温连续激射，输出功率60mW，阈值电流533A/cm-2；激射波长2.91μm激光器实现了室温脉冲激射，阈值电流667A/cm2。激射波长2.97μm激光器实现了室温脉冲激射，阈值电流721A/cm2。

（4）设计制备了高阶DBR光栅量子阱激光器，针对高阶DBR光栅结构特点优化了刻蚀掩膜方法和气体配比，采用接触式光刻技术制备出高阶DBR光栅激光器，研究了光栅凹槽深度和占空比间对选模质量的制约特性，实现了高阶DBR激光器的单纵模室温连续激射，激射波长2微米，边模抑制比22.5dB。

The infrared laser has a significant value in gas detection, laser medication, spatial optical communication and military infrared counteration. The GaSb-based type I quantum well semiconductor laser has a prominent position in the 2 ~ 4μm band infrared laser because of its advantage in small size, high power, high efficiency and good environment adaptability. In-depth study and fabrication of GaSb-based quantum well lasers can not only meet the needs of the field in the infrared band laser, but also has strategic significance. In this paper, the molecular beam epitaxial growth conditions, structural design and fabrication process of high performance GaSb I type quantum well lasers are studied systematically. The preparation process and process characteristics of 2μm high order DBR lasers are studied by using the general technology platform.

(1) The lattice constants of InGaAsSb and AlGaAsSb were calculated by linear interpolation method Vegard's law in GaSb material system. The As composition of different group III components was obtained, and the lattice constants of AlGaInAsSb. The refractive index of InGaAsSb and AlGaAsSb under different wavelengths of 2 ~ 4μm was calculated by Sadao-Adachi approximation model. The optical limiting factor at 2 μm and 3 μm optical field is calculated according to the definition of the optical limiting factor with the former calculated refractive index parameter. The optical limiting factor varies with the thickness of the Al component and the thickness of the waveguide layer. Considering the series resistance and open voltage, the Al component range was limited from 0.5 to 0.7. The optimum waveguide layer thickness is corresponding to lasing wavelength;

(2) The growth parameters of InGaAsSb/AlGaAsSb in the epitaxial growth of MBE were studied. The optimum growth temperature of quantum wells operating at 2.6μm was 500 ℃, and the optimized quantum well strain was about 1.3%. The growth characteristics of AlGaInAsSb were studied. The lattice strain and surface morphology of AlGaInAsSb were characterized by HR-XRD, AFM and optical microscope. The lattice strain changes at different growth temperatures were obtained. The growth temperature of the AlGaInAsSb is similar to that of AlGaAsSb, and the growth window is above Tc + 45 ℃. The growth parameters of the quantum well InGaAsSb/AlGaInAsSb using the quinternary barrier are optimized. The growth of the quantum well above 2.7μm needs to be operated at a lower growth temperature, and 2.7 ~ 3.4μm room temperature PL spectra are obtained by introducing the interface controlling.

(3) According to the optimized growth conditions, 2 ~ 3 μm GaSb-based quantum well laser epitaxial structures were grown with MBE. 2.6μm diode lasers operating at room temperature with continuous wave were fabricated, and the maximum power was 325mW, the threshold current density was 402A / cm-2. 2.75μm diode lasers operating at room temperature with continuous wave were fabricated, and the maximum power was 60mW, the threshold current density was 533A / cm-2. Wavelength was expanded to 2.97μm with room temperature lasing, and the threshold current was 721A / cm-2.

(4) Based on the general processing conditions, a 2μm high-order DBR laser structure was designed. The fabrication of high-order DBR gratings was optimized for needs of the high-quality controllable high-order DBR grating by the optimization of ICP etching. The 2 μm high-order DBR laser device was fabricated by using the previously optimized etching scheme. The relationship between the quality of the mold selection and the depth of the grating groove and the duty ratio was studied. 2μm laser diodes operating at single wavelength mode in RT incontinuous wave were obtained, and the maximum side mode suppression ratio was up to 22.5dB.