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]=1.0x10(14) cm(-2) always accumulate As precipitates, while the planes doped with [Be]=1x10(13) cm(-2) tend to deplete As precipitates. In contrast, the planes doped with [Be]=3 and 2x10(13) cm(-2) exhibit a weak accumulation property when annealed at 700 degreesC, but a depletion property when annealed 800 degreesC. The existence of twins and/or precipitates around the [Be]=1.0x10(14) cm(-2) doped planes found in the as-grown sample suggests a strain-induced mechanism to account for the As precipitates accumulation on these planes. (C) 2003 American Institute of Physics.