Effects of substrate doping and surface roughness on self-assembling InAs/InP quantum dots

The effect of substrate doping (InP:Sn and InP:Fe) and surface morphology of InP (001), misoriented 0.2 degrees off towards [110], on densities and sizes of self-assembled InAs quantum dots was investigated. The dots were deposited on either well-defined terraced surfaces with monolayer high steps,grown at 650 degrees C in the step-flow growth mode, or on more rough InP surfaces prepared at a lower temperature of 500 degrees C. The dot densities were found to vary between 0.5 x 10(10) cm(-2) < rho < 4.0 X 10(10) cm(-2) with otherwise identical growth conditions. The dot densities were lower on terraced surfaces and on Sn-doped substrates in comparison to the rougher surface and on Fe-doped substrates. This very broad scattering of densities indicates that InAs island formation on InP substrates is very sensitive to the choice of substrates and substrate preparation. (C) 2000 Elsevier Science B.V. All rights reserved.