Abstract
Electrical property of Si-doped GaN layers grown on
r-plane sapphire substrates by atmospheric metalorganic vapor-phase epitaxy was investigated. The electron mobility was drastically improved when GaN was grown by means of optimized combinations of growth temperature and low-temperature GaN buffer thickness. The highest room-temperature mobility of 220
cm
2/V
s was recorded at the carrier density of
1.1
×
10
18
cm
-
3
. Temperature dependence of electrical property revealed that the peak mobility of 234
cm
2/V
s was obtained at 249
K. From the slope of carrier density as a function of inverse temperature, the activation energy of Si-donors was evaluated to be 11
meV.