
208 Gallium Nitride (GaN): Physics, Devices, and Technology
an appropriate pH value, the oxidation reaction dominates the process and, hence,
the PEC reaction oxidizes the GaN-based semiconductor surface, forming the
Ga
2
O
3
oxide layer on the GaN surface or the mixed Ga
2
O
3
and Al
2
O
3
oxide layer on
the AlGaN surface. Because the oxide layer was formed through chemical reaction
with the GaN-based semiconductors, the interface between the PEC-grown oxide
layer and the GaN-based semiconductor was nearly free of contamination, result-
ing in a low interface-state density. Moreover, the unique PEC oxidation method is
different from the other conventional ...