HIGH OXYGEN AND CARBON CONTENTS IN GAAS EPILAYERS GROWN BELOW A CRITICAL SUBSTRATE-TEMPERATURE BY MOLECULAR-BEAM EPITAXY

By quantitative secondary ion mass spectroscopy (SIMS) analyses, oxyge n and carbon contents in GaAs epitaxial layers grown by molecular beam epitaxy (MBE) were found to increase significantly when the growth te mperature was reduced below a critical value at about 450 degrees C. T he concentrations of oxygen and carbon in GaAs epilayers grown below t he critical temperature were about 4X10(17) cm(-3) and 3X10(16) cm(-3) , respectively. Meanwhile, impurity accumulation during growth interru ption became faster resulting in even higher interfacial impurity conc entrations. Oxygen and carbon will affect the electrical properties of the GaAs epilayers, especially those grown between 350 degrees C and 450 degrees C where defects related to excess As may not be dominating . (C) 1996 American Institute of Physics.