BANDGAP ENERGY OF CUBIC GAN

Magnetic circular dichroism and time-resolved photoluminescence spectr a were measured for cubic GaN epitaxial layers grown by gas source mol ecular beam epitaxy using NH3 plasma. Pronounced spectral features wer e observed in the magnetic circular dichroism spectra at the same ener gy position as the highest energy signals in reflection and photolumin escence spectra of the epilayers. The time-resolved photoluminescence measurement showed that the corresponding transition has a lifetime of around 15 ps. Considering these results, the exciton bandgap of cubic GaN is estimated to be 3.27 +/- 0.01 eV at 4.2 K. (C) 1997 Elsevier S cience Ltd.