On the kinetics of growth of highly defective GaN epilayers and the origin of the deep trap responsible for yellow-band luminescence

Abstract

The kinetics of growth of GaN/(0001) sapphire heteroepitaxial films have been examined in the relatively low substrate temperature range, 560–640 °C, using the reflection high energy electron diffraction (RHEED) specular reflection intensity monitoring technique. In particular, an alternate element exposure method of growth was employed in which Ga and N atoms were supplied separately (rather than simultaneously, as in conventional molecular beam epitaxy) to the substrate with the inclusion of a time delay between successive Ga flux and N flux exposures. We interpret the observed time dependent recovery of the RHEED specular reflection intensity during the time delay phases to be associated with Ga–N surface molecule migration on Ga-terminated surfaces and the activation energy for this migration process was determined to be 1.45±0.25 eV.

Dislocation reduction through nucleation and growth selectivity of metal-organic chemical vapor deposition GaN

“…The much higher growth rate of GaN in the channel is believed to be the reason for the high densities of point defects in the channel. 28,[36][37][38][39][40][41][42] Also, the high intensity of yellow luminescence in the channel region may indicate excess carbon incorporation due to high growth rate in the channel, low growth temperature (540 C) and low V/III ratio (770) of the initial selective nucleation process. [43][44][45] Fig.…”