{"id":1227,"date":"2010-07-02T11:46:02","date_gmt":"2010-07-02T15:46:02","guid":{"rendered":"https:\/\/wpmu2.mit.local\/?p=1227"},"modified":"2010-07-02T12:09:54","modified_gmt":"2010-07-02T16:09:54","slug":"mocvd-growth-of-geiii-v-heterostructures-and-its-applications","status":"publish","type":"post","link":"https:\/\/wpmu2.mit.local\/mocvd-growth-of-geiii-v-heterostructures-and-its-applications\/","title":{"rendered":"MOCVD Growth of Ge\/III-V Heterostructures and Its Applications"},"content":{"rendered":"

Heteroepitaxy of polar and non-polar semiconductors has long been a challenge for integrating different semiconductor material systems. Previous research in our group has demonstrated high-quality GaAs heteroepitaxy on Ge substrates with low defect density. Anti-phase boundary (APB) formation was suppressed by using offcut substrates and a precisely controlled surface preparation technique [1<\/a>]<\/sup>. Recently, we have demonstrated high-quality heteroepitaxy of Ge on GaAs and tensile-strained Ge on InGaAs by employing surface preparation procedures that ensure a pre-growth surface with a high V-to-III ratio [2<\/a>]<\/sup>. Extending these results, we were able to grow high-quality Ge films on an AlAs underlayer and demonstrate an epitaxial-liftoff technique to transfer Ge films to arbitrary substrates, as shown in Figure 1. The transfer was realized through sacrificial etching of the AlAs underlayer in a diluted HF solution.\u00a0 In another project, we grew a high-quality 40-period GaAs\/AlAs distributed Bragg reflector (DBR) on Ge substrate. Figure 2a shows cross-section TEM image of the first 5 periods of the DBR. After patterning, the Ge substrate was then sacrificially etched via a XeF2<\/sub> gas-phase etching to release the cantilever-shaped DBRs, shown in Figure 2b. These DBR cantilevers form micro-optomechanical resonators with excellent resonant characteristics. Our current project builds on these results and explores a method to make GaAs-on-insulator substrate on the 6-inch scale via lateral etching of an epitaxial Ge sacrificial layer.<\/p>\n\n\t\t