Effects of Heat Treatment on the Structural Defects and Electrical Properties of GaAs

抄録

Behavior of structural defects in bulk GaAs during various heat treatmentprocesses was investigated. Results showed that the formation temperature ofAs-related dislocation loops and precipitates in an As-rich HB (HorizontalBridgman) GaAs is around 650°C, and their formation process is reversible andcritically affected by the cooling rate of crystals from high temperature. Inthe case of LEC (Liquid Encapsulated Czochralski) GaAs, precipitates formedon dislocations at the temperature range of 650°C-950°C, whereas point defectcluster around dislocations formed at 650°C-850°C. Based upon this observation, it was proposed that the excess As existing in GaAs crystals condenses as pointdefects, dislocation loops, and/or As precipitates, depending upon cooling ratefrom high temperature, presence of nucleation sites (dislocations), and degreeof nonstoichiometry. It was also observed that concentration of EL 2 defectsin the HB crystal tend to increase as the structural defects dissolve, indicatingthat the behavior of the structural defects can be closely related to that of theelectrically important EL 2 defects.