GaN layers having the zinc blende and wurtzite structures can be selectively deposited on (111)A and (1¯1¯1¯)B GaAs substrates by varying the growth temperature. Using the growth temperature as a variable, layers having the two structures have been sequentially deposited. The as‐grown structures have been examined by cross‐sectional high resolution electron microscopy. Results indicate that the two phases once formed are structurally stable in the temperature range examined. Furthermore, the transition from GaN (zinc blende) to GaN (wurtzite) is sharp, whereas a faulted region is observed during the reverse transition. Arguments have been developed to rationalize these observations. ©1995 American Institute of Physics.