高速率沉积磁控溅射技术制备Ge点的退火生长研究

Study on the annealing growth of Ge dots at high deposition rate by using magnetron sputtering technique

采用磁控溅射技术在Si衬底上以350?C沉积14 nm的非晶Ge薄膜,通过退火改变系统生长热能,实现了低维Ge/Si点的生长.利用原子力显微镜(AFM)和拉曼(Raman)光谱所获得的形貌和声子振动信息,对Ge点的形成机理和演变规律进行了研究.实验结果表明:在675?C退火30 min后,非晶Ge薄膜转变为密度高达8.5×109cm-2的Ge点.通过Ostwald熟化理论、表面扩散模型和对激活能的计算,很好地解释了退火过程中,Ge原子在Si表面迁移、最终形成纳米点的行为.研究结果表明用高速沉积磁控溅射配合热退火制备Ge/Si纳米点的方法,可为自组织量子点生长实验提供一定的理论支撑.

The 14 nm thick Ge thin films are firstly deposited on Si substrate at 350 ℃ by using the magnetron sputtering technique, then the Ge/Si dots are successfully fabricated by annealing those Ge films. According to the morphology and phonon vibration information obtained by AFM and Raman spectroscopy, the formation and evolution mechanism are studied in detail. Experimental results indicate that the amorphous Ge films have been converted to Ge dots with a density of 8.5 × 10^9 cm^-2 after 675 ℃ annealing for 30 min. By using Ostwald ripening theory, surface diffusion model, and calculation of the activation energy, the surface transfer and the dot formation behavior of Ge atoms can be well interpreted. Based on the fabrication technique of Ge/Si nanodots at a high deposition rate combined with the thermal annealing, we have provided a theoretical support for the experiment on self-assembled growth of Ge quantum dots.