General behavior of the In/GaAs couple under prolonged sintering

The effects of interaction between a thick In layer and heat-treated GaAs at 570°C are studied with Scanning Electron Microscopy (SEM), Secondary Ion Mass Spectrometry (SIMS), Rutherford Backscattering Spectrometry (RBS), X-Ray Diffraction (XRD) and Nomarski microscopy. It is shown that, besides the well-known InGaAs crystallites which epitaxially grow upon dissolution of the substrate, an array of In-rich dendrites is observed whose density correlates with the density of the crystal dislocations. The driving force for In to protrude along the dislocations to eventually form In(Ga)As spikes is apparently excess arsenic reported to be present in the vicinity of the individual dislocations. It is postulated that the existing data concerning the coefficient of classical diffusion of In in GaAs may be overestimated by a factor of 10⁶.