Epitaxial Growth of Semi-Insulating GaAs

The objective of this program is to develop techniques for the vapor- phase growth of high-resistivity epitaxial layers of gallium arsenide on semi- insulating gallium arsenide substrates. A capability to grow such layers of high-quality material with minimum structural defects and good surface quality for use as buffer layers prior to the growth of active layers for such devices as FETs and TELDS will eliminate the device performance problems caused by poor and inconsistent substrate quality. During the first quarter, a vapor-phase GaAs reactor and its associate gas handling system were designed and constructed. Preliminary test runs were performed to check system operation under normal operating conditions. In the second quarter, both undoped and Cr-doped high- resistivity GaAs epitaxial layers were grown. The surface morphology of the high-resistivity layers was excellent. During the second quarter, the investigation of a number of techniques was begun in order to develop a capability for characterizing both substrate material and high-resistivity epitaxial layers. This report will describe progress in all of these areas.