Dual accumulation and depletion behaviors of the arsenic precipitation in low-temperature-grown Be delta-doped GaAs.

The precipitation of arsenic in annealed Be delta-doped GaAs grown by low-temperature molecular-beam epitaxy has been studied using transmission electron microscopy. It was found that the planes doped with [Be] = 1.0 10[sup 14] cm[sup -2] always accumulate As precipitates, while the planes doped with [Be] = 1 × 10[sup 13] cm[sup -2] tend to deplete As precipitates. In contrast, the planes doped with [Be] = 3 and 2 × 10[sup 13] cm[sup -2] exhibit a weak accumulation property when annealed at 700 °C, but a depletion property when annealed 800 °C. The existence of twins and/or precipitates around the [Be]= 1.0 × 10[sup 14] cm[sup -2] doped planes found in the as-grown sample suggests a strain-induced mechanism to account for the As precipitates accumulation on these planes. [ABSTRACT FROM AUTHOR]