Epitaxial growth of semi-insulating Ga-As

The objective of the program is to develop techniques for the vapor phase growth of high resistivity epitaxial layers of GaAs on semi-insulating (SI) GaAs substrates. A capability to grow high resistivity buffer layers with minimum structural defects prior to the growth of active device layers would eliminate device performance problems caused by poor and inconsistent substrate quality. During the program a reactor and its associated gas handling system was built. Both undoped and chromium doped high resistivity epitaxial layers were grown with excellent surface morphology. In order to determine the properties of the material grown, a parallel effort in material characterization has been carried out. This effort has included measurement of electrical and photoconductive properties as well as the employment of various analytical techniques to determine the concentrations of chromium introduced during the material growth.