90-DEGREES DOUBLE REFLECTION HIGH-ENERGY ELECTRON-DIFFRACTION EXPERIMENTS ON VICINAL SURFACES OF GAAS

Reflection high-energy electron diffraction (RHEED) experiments record ing the intensity of the specular beam in two azimuths have been carri ed out simultaneously. The critical temperature for the transition fro m 2D nucleation to step-flow growth was simultaneously estimated in th e [($) over bar 110] and [110] directions by observing the disappearan ce of RHEED intensity oscillations on GaAs(001) substrates 2 degrees m isoriented towards GaAs(111)A. It was found that the oscillations disa ppear at a lower substrate temperature in the [110] azimuth. The diffe rence in the transition temperatures was 25 degrees C.