Abstract
The flow-rate-modulated chemical beam epitaxy (FM-CBE) method was developed and implemented on the basis of the discussion of the desorption velocities of absorbed species originating from N source gas [MMHy, (CH3)N2H3] for decreasing the residual carbon (C) concentration in GaAsN films. In this method, the Ga source [TEGa, Ga(C2H5)3] was supplied intermittently, while the As [TDMAAs, As(N(CH3)2)3] and N sources (MMHy) were supplied continuously. Below growth temperatures of 440 °C, the residual C concentrations in GaAsN films was reduced to 1/10 that in conventional CBE films, with no change in N concentration. However, above 440 °C, N concentration decreased drastically with FM-CBE. It was concluded that the reduction in C concentration by FM-CBE was attributed to the decrease in –NHCH3 coverage on the growing surface by –NH2 substitution during the intermittence of the TEGa flow. FM-CBE was an effective method for decreasing residual C concentration while maintaining the N concentration in GaAsN films below 440 °C.