Reduction of Be diffusion in GaAs by migration enhanced epitaxy, and the effect of heat treatment on the electrical activation and mobility

It has been demonstrated that the migration-enhanced epitaxy (MEE) method can be used to grow high-quality GaAs at low substrate temperature. Annealed MEE layers are shown to have hole concentration mobility, surface morphology, and optical characteristics comparable to those of MBE (molecular beam epitaxy) layers. Because of the reduction of Be diffusion in annealed MEE layers, relative to MBE layers, the MEE method can replace the conventional MBE method for device applications which require high hole concentration with small Be diffusion. As the anneal time increases, the hole sheet density increases and reaches some final value. A higher anneal temperature results in high electrical activation in a shorter anneal time. For annealing below 1000°C, the electrical activation monotonically increases as the anneal temperature increases. For 15-s anneal time, the hole sheet and the mobility peak at the anneal temperatures of 1000 and 900°C, respectively