Band-Edge Potentials of n-Type and p-Type GaN

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Abstract
The band-edge potentials of p-GaN in aqueous solutions were examined with photocurrent measurements, and those of n-GaN were examined with both photocurrent measurements and impedance spectroscopy. The measured band-edge potentials were different for both the different materials and the different measurement techniques. These differences are attributed to differences in the interface charging due to slow charge-transfer kinetics at the interface between the semiconductor and the solution. Using photocurrent measurements, the conduction band-edge potential was Φc,s=(−1.092−0.063×pH)Φc,s=(−1.092−0.063×pH) V vs. a standard calomel electrode (SCE) for p-GaN and Φc,s=(−0.538−0.046×pH)Φc,s=(−0.538−0.046×pH) V SCE for n-GaN. Using impedance spectroscopy, the conduction band-edge potential for n-GaN was Φc,s=(−0.816−0.047×pH)Φc,s=(−0.816−0.047×pH) V SCE. © 2003 The Electrochemical Society. All rights reserved.