Reduction of Residual Carbon in GaAsN Films Grown by Chemical Beam Epitaxy

Crystal quality of GaAsN films can be improved by using chemical beam epitaxy method for low-temperature growth. However, low-temperature growth increases carbon (C) incorporation in the films, which degrades their electrical properties. To reduce the C concentration in the films, C incorporation process was investigated in view of the surface reaction of nitrogen (N) sources on a substrate surface, and monomethylhydrazine (MMHy) and 1,1-dimethylhydrazine (DMHy) were compared. When MMHy was used as an N source, the C concentration in GaAsN drastically increases below 380degC than that in GaAs due to insufficient CH_X desorption. In the case of DMHy, N(CH₃)₂ is desorbed more readily than CH_X. Therefore, the C concentration can then be reduced by using DMHy