Luminescence spectroscopy of GaN in the high-temperature regime from room temperature to 900 degrees C

We have measured the optical luminescence spectrum of GaN from the near inf rared to the near ultraviolet at elevated temperatures. Despite intense bla ckbody radiation above 600 degrees C, luminescence is observable at 3 eV or greater at temperatures as high as 900 degrees C, i.e., including near-ban d-edge emissions over the entire range of GaN growth temperatures. Elevated -temperature measurements also reveal thermally activated quenching of the midgap "yellow" defect luminescence. These results show that electron beams already used to monitor molecular-beam epitaxy growth can also provide tem perature and defect information during the growth process. (C) 2000 America n Institute of Physics. [S0003-6951(00)03131-4].