Microprecipitates in Semi-Insulating GaAs Single Crystals

摘要

The microprecipitates in the as-grown undoped and In-doped semi-insulating GaAs single crystals have been ex-amined by JEM 200 CX transmission electron microscope.The microprecipitates consist of GaAs polycrystalline grainsof 5～100nm in size have been evidenced in dislocated crystals.Energy dispersive X-ray analysis shows that themieropreeipitates are predominately arsenic-rich GaAs.The As/Ga atomic ratio of the microprecipitates in In-dopedcrystal is higher than that of undoped crystal.It is suggested that the formation of the microprecipitates may be inducedby the local fluctuation of compositional undercooling during crystal growth.