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, oxygen and carbon contents in GaAs epitaxial layers grown by molecular beam epitaxy (MBE) were found to increase significantly when the growth temperature was reduced below a critical value at about 450 °C. The concentrations of oxygen and carbon in GaAs epilayers grown below the critical temperature were about 4×1017 cm−3 and 3×1016 cm−3, respectively. Meanwhile, impurity accumulation during growth interruption became faster resulting in even higher interfacial impurity concentrations. Oxygen and carbon will affect the electrical properties of the GaAs epilayers, especially those grown between 350 °C and 450 °C where defects related to excess As may not be dominating.