Abstract
The electrical and optical properties of Mg-doped
a- and
c-plane GaN films grown by metalorganic vapor phase epitaxy were systematically investigated. The photoluminescence spectra of Mg-doped
a- and
c-plane GaN films exhibit strong emissions related to deep donors when Mg doping concentrations are above 1×10
20
cm
−3 and 5×10
19
cm
−3, respectively. The electrical properties also indicate the existence of compensating donors because the hole concentration decreases at such high Mg doping concentrations. In addition, we estimated the
N
D
/N
A
compensation ratio of
a- and
c-plane GaN by variable-temperature Hall effect measurement. The obtained results indicate that the compensation effect of the Mg-doped
a-plane GaN films is lower than that of the Mg-doped
c-plane GaN films.