Migration of Si in δ-doped GaAs

Abstract

Si atomic plane or delta ( delta )-doping of GaAs during MBE has been investigated using SIMS profiling optimised for high depth resolution. For layers in which almost all the Si atoms act as donors, post-growth diffusion occurs at the growth temperature with a diffusion coefficient estimated to be 9*10-17 cm2 s-1 at a substrate temperature of 550 degrees C. At temperatures greater than about 550 degrees C, a marked preferential migration towards the surface is observed, which may be due to surface segregation or possibly enhanced diffusion.