砷化銦鎵/砷化鎵和砷化鋁鎵/砷化鎵異質結構在低基板溫度下（∼230℃）以分子束磊晶成長，這導致過多的砷併入在磊晶層裡。在之後的退火過程中（500∼700℃），這些過多的砷形成砷析出物。砷析出物的粗化過程隨著退火溫度和時間的增加愈趨於顯著。
在退火溫度為500℃、退火時間30秒的情況下，靠近砷化鋁鎵/砷化鎵異質結構的介面有明顯的砷析出物聚合區和砷析出物空乏區。此外，在退火溫度600℃的條件下，砷析出物在靠近砷化銦鎵/砷化鎵異質結構的介面處形成兩排列陣；在更高的退火溫度下（~700℃），砷析出物則偏向於散亂排列。這些結果是由砷原子擴散越過異質結構的介面所造成。砷原子擴散的過程可由降低砷析出物/基體的介面能和介面附近的晶格應變來解釋。

對於在較高退火溫度和較長退火時間下，砷析出物的粗化過程是一種“奧斯特華熟化”的過程。藉由不同條件的退火過程可以來控製是後砷析出物的大小和分佈，這種退火後形成的兩相系統（砷析出物/基體）在電子或光電元件上有很大的應用及幫助。

In this study, InGaAs/GaAs and AlGaAs/GaAs multiple quantum well (MQW) structures have been grown by molecular beam epitaxy (MBE) at low substrate temperatures (~230℃). This results in an excess of arsenic incorporated in the epilayers and upon subsequent annealing (500~700℃), the excess arsenic precipitates. The coarsening of the As clusters is observed to increase with the temperature or time of annealing.
In the AlGaAs/GaAs MQW structures, there are obvious As precipitates accumulation zones (PAD) and precipitates depletion zones (PDZ) near the interfaces of the AlGaAs/GaAs heterostructure annealed at 500℃ for 30s. For the InGaAs/GaAs MQW structures, arsenic precipitates form two dot arrays near each InGaAs/GaAs interface when annealed at 500 and 600℃ and lose this confinement at higher annealing temperature (~700℃). The results are due to the diffusion of arsenic atoms across the interfaces of the heterostructures. The process of arsenic precipitates in the LT heterostructure can be explained by the reduction in the arsenic precipitates/matrix interfacial energy or the lattice-mismatch strain near the interfaces.

For an increase of annealing temperature and time, the coarsening of As precipitates follows the process of Ostwald ripening. The annealing processes controlling the final sizes and distribution of As precipitates are important, and the properties of the two-phase system are useful in many electronic and optoelectronic applications.

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