Proper In deposition amount for on-demand epitaxy of InAs/GaAs single quantum dots

• Published in: Chinese physics B Vol. 25; no. 10; pp. 452 - 458
• Main Author: 尚向军 徐建星 马奔 陈泽升 魏思航 李密峰 查国伟 张立春 喻颖 倪海桥 牛智川
• Format: Journal Article
• Language: English
• Published: 01.10.2016
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/25/10/107805

The test-QD in-situ annealing method could surmount the critical nucleation condition of InAs/GaAs single quantum dots（SQDs） to raise the growth repeatability.Here,through many growth tests on rotating substrates,we develop a proper In deposition amount（θ） for SQD growth,according to the measured critical θ for test QD nucleation（θc）.The proper ratio θ/θc,with a large tolerance of the variation of the real substrate temperature(Tsub),is 0.964-0.971 at the edge and> 0.989 but < 0.996 in the center of a 1/4-piece semi-insulating wafer,and around 0.9709 but < 0.9714 in the center of a 1/4-piece N+ wafer as shown in the evolution of QD size and density as θ/θc varies.Bright SQDs with spectral lines at 905 nm-935 nm nucleate at the edge and correlate with individual 7 nm-8 nm-height QDs in atomic force microscopy,among dense 1 nm-5 nm-height small QDs with a strong spectral profile around 860 nm-880 nm.The higher Tsub in the center forms diluter,taller and uniform QDs,and very dilute SQDs for a proper θ/θc:only one 7-nm-height SQD in25 μm2.On a 2-inch（1 inch = 2.54 cm） semi-insulating wafer,by using θ/θc = 0.961,SQDs nucleate in a circle in 22%of the whole area.More SQDs will form in the broad high-Tsub region in the center by using a proper θ/θc.