鍺量子點於凹洞圖形化矽(001)基板上之成核特性與機制

Abstract

The nucleation properties of Ge dots have been extensively researched because of its potential for photodetectors and compatibility with Si technology. In general, Ge dots grown on a blank Si substrate are randomly positioned and exhibit a broad size distribution, which limits its realistic applications. In this dissertation, we demonstrated that the nucleation properties of Ge dots can be controlled with pit-patterned Si substrate. These well-controlled Ge dots are symmetrically located with respect to and exhibit an elliptical dome shape whose major axis is oriented along . The dot areal density is up to 4×109 /cm2, and the means of major axis, minor axis, and height of the dots are 84 ± 7 nm, 73 ± 6 nm, and 4 ± 1 nm, respectively. Besides, we found that the pre-growth heat treatment process, a conventional process for native oxide desorption before growth, will drastically transforms the structure of the pre-patterned pits on Si(001) substrates into truncated inverted pyramids (TIPs) and crucially determines the nucleation position, shape, and spatial orientation of the subsequently grown Ge dots. The surface chemical potential of the TIP was also calculated and compared with the observed nucleation properties of Ge dots. These results raise the possibility of realizing high-performance Ge quantum dot photodetectors and provide further understanding of the growth of Ge dots on pit-patterned Si substrates.