Eur. Phys. J. Appl. Phys.
Volume 36, Number 2, November 2006
|Page(s)||125 - 130|
|Section||Nanomaterials and Nanotechnologies|
|Published online||28 October 2006|
Self-regulated charge transfer and band tilt in nm-scale polar GaN films
Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
2 Department of Chemical and Materials Engineering, and Electrical Engineering, Ira A. Fulton College of Engineering, Arizona State University, Tempe, AZ 85287-6006, USA
Corresponding author: email@example.com
Revised: 26 April 2006
Accepted: 25 August 2006
Published online: 28 October 2006
Using first-principles calculation for the electronic structures of nm-scale  GaN freestanding films, it is found that the Ga-terminated surface (SGa) has a positive electrostatic potential, while the N-terminated surface has a negative electrostatic potential (SN), so that the energy bands tilt upwards from SGa to SN. Additionally, it is determined that an intrinsic self-regulated charge transfer across the film limits the electrostatic potential difference across the film, which renders the local conduction band energy minimum at SGa approximately equal to the local valence band energy maximum at SN. This effect is found to occur in films thicker than ~4 nm. If the dangling-bond/surface states at both SGa and SN are passivated by pseudo-hydrogen atoms, the tilt of energy bands is similar, though the cross-film potential is reduced due to the extra H5/4-Ga and N-H3/4 dipole layers.
PACS: 73.61.Ey – III-V semiconductors / 73.90.+f – Other topics in electronic structure and electrical properties of surfaces, interfaces, thin films, and low-dimensional structures
© EDP Sciences, 2006
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