MOCVD-InAs/GaSb DBR结构材料的特性研究

Characteristic Study on MOCVD-InAs/GaSb DBR

本研究采用MOCVD技术在GaSb衬底上制备InAs与GaSb交替生长层构成的分布布喇格反射镜(DBR)材料。由于InAs与GaSb材料晶格匹配良好,且折射率差较大,因此用这两种材料交替生长构成的DBR结构,在较低生长周期时即可获得较高的反射率。将其引入共振腔增强型红外探测器结构,做为共振腔的腔体,将大大改善器件性能,实现红外光的高灵敏度室温探测。根据多膜增反原理,膜层反射率随膜层周期增加而增加,理论计算结果显示InAs/GaSb DBR结构工作波长为2.4μm,周期为22时,膜层反射率即可高于80.11%。我们用扫描电子显微镜,X-ray射线衍射,反射光谱测量等分析手段,对InAs/GaSb DBR结构材料的物理性能进行表征。结果表明,我们已经成功获得高质量的晶格匹配的InAs、GaSb单晶薄膜,以及InAs/GaSb交替生长组成的不同周期的DBR结构材料。反射光谱测量显示,InAs/GaSb DBR反射率随膜层周期数增加而增加,当InAs/GaSb DBR周期数为22时,其反射率约为44.27%。

The high quality unintentionally doped GaSb, InAs epilayers and Distributed Bragg Reflectors formed by InAs/GaSb alternative layers have been grown on the Te-doped high quality （100）GaSb substrates in an atmospheric or low pressure metal organic chemical vapor deposition system made up in our laboratory. The source materials are TMIn, TMGa, TMSb and AsH3. The growth temperature of the InAs and GaSb is 400℃ and 600℃ ,respectively. The pressure is 9.3 × 10^3pa in the reactor room. InAs and GaSb is lattice matched and they are lattice matched with the quaternary GalnAsSb layers. The Distributed Bragg Reflectors are formed by laying down alternating layers of InAs and GaSb with a difference in the refractive index. The function of the reflectivity of the DBR varied with the wavelength and the period number of the DBR. According to the principle of the light through multiple-layer reflective films its reflection will be increased, the reflectivity of the DBR rapidly increased with the increase of period number of DBR when the center wavelength is 2.4μm. The reflectivity of the DBR is greater than 80% as the period number of the DBR is 22. The experimental results have shown that we have successfully obtained the Distributed Bragg Reflectors, and their period numbers are 3,4,6,9, 15,22, respectively. The reflectivity of DBR is lower than the theoretical results. The reflectivity of DBR increased with increase of period number of DBR, but the reflectivity of DBR with period number 22 is only 44.27%.