摘要
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（θ;）.The proper ratio θ/θ;,with a large tolerance of the variation of the real substrate temperature(T;),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/θ;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 T;in the center forms diluter,taller and uniform QDs,and very dilute SQDs for a proper θ/θ;:only one 7-nm-height SQD in25 μm;.On a 2-inch（1 inch = 2.54 cm） semi-insulating wafer,by using θ/θ;= 0.961,SQDs nucleate in a circle in 22%of the whole area.More SQDs will form in the broad high-T;region in the center by using a proper θ/θ;.
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(θ_c).The proper ratio θ/θ_c,with a large tolerance of the variation of the real substrate temperature(T_(sub)),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/θ_c 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 T_(sub) in the center forms diluter,taller and uniform QDs,and very dilute SQDs for a proper θ/θ_c:only one 7-nm-height SQD in25 μm^2.On a 2-inch(1 inch = 2.54 cm) semi-insulating wafer,by using θ/θ_c = 0.961,SQDs nucleate in a circle in 22%of the whole area.More SQDs will form in the broad high-T_(sub) region in the center by using a proper θ/θ_c.
基金
supported by the National Key Basic Research Program of China(Grant No.2013CB933304)
the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB01010200)
the National Natural Science Foundation of China(Grant No.65015196)
