Absence of Fermi-level pinning at cleaved nonpolar InN surfaces.
Prior experimental work had found that the Fermi level at InN growth surfaces is pinned well above the conduction band edge, leading to strong surface band bending and electron accumulation. Using cross-sectional scanning photoelectron microscopy and spectroscopy, we show definitive evidence of unpinned Fermi level for in situ cleaved a-plane InN surfaces. To confirm the presence or absence of band bending, the surface Fermi level relative to the valence band edge was precisely measured by using both the Fermi edge of Au reference sample and the core level of ultrathin Au overlayer. It is confirmed that flat surface bands only occur at cleaved nonpolar surfaces, consistent with the recent theoretical predictions.
Wu
Chung-Lin
CL
Department of Physics, National Tsing-Hua University, Hsinchu 30013, Taiwan.
Lee
Hong-Mao
HM
Kuo
Cheng-Tai
CT
Chen
Chia-Hao
CH
Gwo
Shangjr
S