Characterization of the Semi-Insulating Properties of Undoped GaAs Grown by the Horizontal Bridgman Technique

Two inch and three inch diameter undoped semi-insulating GaAs has been grown by a modified horizontal Bridgman technique. Due to the reduced thermal gradients used, this method promises more uniform, low EPD material than can be produced by the undoped LEC process. By using pyrolytic boron nitride boats and controlling the growth environment, to reduce background impurities we have overcome the historical problems in producing undoped semi-insulating GaAs by the horizontal Bridgman technique. Van Der Pauw measurements show that this material has resistivities in the 10
⁷
- 10
⁸
ohm-cm range. Hall measurements indicate mobilities 4000 cm
²
/V-sec. Preliminary indications are that the dominant level has activation energy of 0.71 eV.