Improvement of crystal quality of n-AlGaN by alternate-source-feeding metal organic vapor phase epitaxy

The crystal quality of AlGaN layers was improved using alternate-source-feeding epitaxy (ASFE) in low-pressure (LP) metal organic vapor phase epitaxy (MOVPE). The green emission of photoluminescence (PL) from the AlGaN clad layer was reduced, indicating that point defects such as Ga or Al vacancy were reduced by ASFE. On the other hand, the full width at half maximum (FWHM) of the X-ray rocking curve was not improved at all and the dislocation density observed by transmission electron microscopy (TEM) was not reduced by ASFE. Furthermore, the yellow emission from GaN/AlGaN multi-quanturn well (MQW) grown by conventional-simultaneous source-feeding epitaxy (SSFE) on the ASFE AlGaN clad layer was also reduced. This indicates that the improvement of the crystal quality of the AlGaN clad layer influences the crystal quality of the MQW grown on it.