Polarization-dependent electron affinity of LiNbO₃ surfaces

Authors

W.-C. Yang, North Carolina State University, Raleigh
B. J. Rodriguez, North Carolina State University, RaleighFollow
Alexei Gruverman, University of Nebraska-LincolnFollow
R. J. Nemanich, North Carolina State University, Raleigh

Date of this Version

September 2004

Comments

Published in Appl. Phys. Lett., Vol. 85, No. 12, 20 September 2004. Copyright © 2004 American Institute of Physics. Used by permission.

Abstract

Polar surfaces of a ferroelectric LiNbO₃ crystal with periodically poled domains are explored using UV-photoelectron emission microscopy (PEEM). Compared with the positive domains (domains with positive surface polarization charges), a higher photoelectric yield is found from the negative domains (domains with negative surface polarization charges), indicating a lower photothreshold and a corresponding lower electron affinity. The photon-energy-dependent contrast in the PEEM images of the surfaces indicates that the photothreshold of the negative domains is ~4.6 eV while that of the positive domains is greater than ~6.2 eV. We propose that the threshold difference between the opposite domains can be attributed to a variation of the electron affinity due to opposite surface dipoles induced by surface adsorbates.