Detection and analysis of hexagonal phase generation in selective-area growth of cubic GaN by metaloganic vapor phase epitaxy

The hexagonal phase generation m selective-area, growth of cubic GaN (SAG c-GaN) on patterned GaAs (100) substrates by low-pressure (160 Torr) metaloganic vapor phase epitaxy (MOVPE) have been analyzed by X-ray diffraction (XRD) and cathodoluminescence (CL). We found that the growth feature and hexagonal phase generation of SAG c-GaN are much dependent on mask stripe orientation and fill factor (ratio of opening width to pattern period). XRD demonstrated that the SAG c-GaN condensed m cubic phase for all samples. CL images show the SAG c-GaN on the [011]-and the [0-11]-stripe patterns include hexagonal phase (360 nm) as well as the cubic phase (381 nm). On the other hand, the emission of hexagonal phase (360 nm) was not observed in SAG c-GaN on [001]-stripe pattern It is clear that the generation of hexagonal phase GaN easily occurs for SAG c-GaN on the [011]-and the [0-11]-stripe patterns indicated by the dominant emissions at 360 rim and 381 mi. These results suggest that the generation of hexagonal phase GaN could be controlled by the use of mask stripe orientation and fill factor The nature of hexagonal phase generation responsible for the CL distribution is discussed.