TEMPERATURE-MEDIATED PHASE SELECTION DURING GROWTH OF GAN ON (111)A AND ((1)OVER-BAR(1)OVER-BAR(1)OVER-BAR)B GAAS SUBSTRATES

GaN layers having the zinc blende and wurtzite structures can be selec tively deposited on (111)A and ((111) over bar)B GaAs substrates by va rying the growth temperature. Using the growth temperature as a variab le, layers having the two structures have been sequentially deposited. The as-grown structures have been examined by cross-sectional high re solution electron microscopy. Results indicate that the two phases onc e formed are structurally stable in the temperature range examined. Fu rthermore, the transition from GaN (zinc blende) to GaN (wurtzite) is sharp, whereas a faulted region is observed during the reverse transit ion. Arguments have been developed to rationalize these observations. (C) 1995 American Institute of Physics.