Abstract
The authors studied the photoelectrochemical properties dependent on carrier concentration of
n
-type GaN. The photocurrent at zero bias became the maximum value at the carrier concentration of
1.7
×
10
17
cm
−
3
. Using the sample optimized carrier concentration, the authors achieved
H
2
gas generation at a Pt counterelectrode without extra bias for the first time. The authors also discussed the mechanism of the dependence of photocurrent on the carrier concentration of GaN.