Promoting strain relaxation of Si_0.72Ge_0.28 film on Si (1 0 0) substrate by inserting a low-temperature Ge islands layer in UHVCVD

详细信息    查看全文

• 作者：Zhiwen Zhou ; Zhimeng Cai ; Cheng Li ; Hongkai Lai ; Songyan Chen ; Jinzhong Yu
• 关键词：Relaxed buffer ; SiGe film ; LT-Ge layer ; Strain relaxation ; UHVCVD
• 刊名：Applied Surface Science
• 出版年：2008
• 出版时间：30 December 2008
• 年：2008
• 卷：255
• 期：5, Part 2
• 页码：2660-2664
• 全文大小：769 K

文摘

A flat, fully strain-relaxed Si_0.72Ge_0.28 thin film was grown on Si (1 0 0) substrate with a combination of thin low-temperature (LT) Ge and LT-Si_0.72Ge_0.28 buffer layers by ultrahigh vacuum chemical vapor deposition. The strain relaxation ratio in the Si_0.72Ge_0.28 film was enhanced up to 99 % with the assistance of three-dimensional Ge islands and point defects introduced in the layers, which furthermore facilitated an ultra-low threading dislocation density of 5 × 10⁴ cm⁻² for the top SiGe film. More interestingly, no cross-hatch pattern was observed on the SiGe surface and the surface root-mean-square roughness was less than 2 nm. The temperature for the growth of LT-Ge layer was optimized to be 300 °C.