Effects of growth conditions on the incorporation of oxygen in AlGaN layers grown by plasma assisted molecular beam epitaxy

Using secondary ion mass spectroscopy we have shown that oxygen incorporati on in AlGaN films is dependent upon the III/V growth conditions and the gro wth temperature of the films. AlGaN films grown under excess group III cond itions (Ga-rich) exhibited step flow growth and at least a factor of 3 less oxygen incorporation than films grown under excess group V (N-rich conditi ons). We found that oxygen incorporation into AlGaN decreases as the growth temperature is increased. The lowest oxygen levels were achieved by growin g at 750 degreesC under Ga-rich growth conditions. Possible sources of unwa nted oxygen are discussed. (C) 2000 American Institute of Physics. [S0003-6 951(00)01346-2].