Polarity control of GaN epitaxial layers in MBE growth

The mechanism of polarity control in molecular beam epitaxy (MBE) growth of GaN epitaxial layers has been investigated using N-face of bulk GaN crystal. The (6×6) reflection high-energy electron diffraction (RHEED) reconstruction patterns were observed from GaN epitaxial layers on high-temperature-grown buffer layers over N-face bulk GaN after cooling. On the other hand, the (2×2) RHEED reconstruction patterns were observed from GaN epitaxial layers on In-doped GaN epitaxial layers over N-face bulk GaN after cooling. These results suggest that N-polarity can be reversed to Ga-polarity by In doping but not by the deposition of high-temperature-grown buffer layers.

GaN

MBE

lattice polarity

high-temperature-grown AlN buffer layers

In doping