Evidence of two-species nucleation of InAs islands on (100) and (111)B GaAs substrates

Abstract

The nucleation of InAs islands on (100) and (111)B GaAs substrates during metalorganic chemical vapor deposition has been investigated via scanning electron microscopy. The measured values of island density are 4–5 orders of magnitude smaller than those predicted using conventional one-species nucleation theory. In addition, the effect of an increase in arsine flow on island density is opposite in sense for the two substrate orientations. To explain these observations, we further develop a two-species picture of nucleation—originally proposed by Stoyanov [Appl. Phys. A 50, 349 (1990)]—in which the InAs island density is an explicit function of both the indium flux and the arsenic partial pressure at the growth interface. This more realistic physical model is in good agreement with the complete set of experimental data.