Schematic Diagram of the HVPE reactor.
Mask with star shaped pattern, with stripes opened at 5° angular increment to determine optimal stripe orientation and differences in lateral growth rates.
Areas of parallel stripes. (top: SEM top view of mask, bottom: stripe/mask widths)
Photoluminescence spectrum of GaN/Al2O3.
Top view of GaN/Al2O3 (optical microscope).
Top view of a growth pyramid (optical microscope).
Growth on star shaped pattern (SEM, top view). Differences in lateral growth rates can clearly be seen.
Growth on star shape pattern (SEM, tilted view), change of stripe cross-sections from triangular in <110> direction to trapezoidal in <1
00> direction shape reflects differences of lateral growth rates.
Growth on parallel stripes 10 µm/10 µm in <100> direction before coalescence
Growth on parallel stripes 5 µm/5 µm in <100> direction, coalescence of GaN