Relaxed SiGe-on-insulator fabricated by dry oxidation of sandwiched Si/SiGe/Si structure

An improved technique is demonstrated to fabricate silicon-germanium on insulator (SGOI) starting with a sandwiched structure of Si/SiGe/Si. After oxidation of the sandwiched structure and successive annealing, a relaxed SiGe-on-insulator (SGOI) structure is produced. Our results indicate that the added Si cap layer is advantageous in suppressing Ge loss at the initial stage of SiGe oxidation and the subsequent annealing process homogenizes the Ge fraction. Raman measurements reveal that the strain in the SiGe layer is fully relaxed at high oxidation temperature (∼1150 °C) without generating any threading dislocations and crosshatch patterns, which generally exist in the relaxed SiGe layer on bulk Si substrate.