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NANOSCOPIC STUDY OF ZnO FILMS BY ELECTRON BEAM INDUCED CURRENT IN THE SCANNING TUNNELING MICROSCOPE

A. Urbieta1, P. Fernández1, J. Piqueras1,* , E. Vasco2, C. Zaldo2

Affiliation

  1. Departamento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
  2. Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid, Spain

Abstract

Scanning tunnelling microscopy and spectroscopy have been used to characterize electrically active grain boundaries in pulsed laser deposited ZnO films with grain sizes in the range 216- 500 nm. The p-type behaviour at the boundary is evidenced by local STM conductance spectra, which reveal boundaries with a n-p-i-p-n structure. In addition, local differential conductance measurements show higher surface band gap at the grain boundaries than in the grain interior, which is related to the space charge at the boundaries. The beam induced current mode of the STM has been used to image electrically active grain boundaries with a resolution of few nanometers in the different films. It is demonstrated that in some of the small grains the space charge region extends to the whole grain area so that no electrical barrier can be related to the grain boundary..

Keywords

Scanning tunneling spectroscopies, Interface states, Zinc oxide.

Submitted at: Feb. 3, 2004
Accepted at: March 15, 2004

Citation

A. Urbieta, P. Fernández, J. Piqueras, E. Vasco, C. Zaldo, NANOSCOPIC STUDY OF ZnO FILMS BY ELECTRON BEAM INDUCED CURRENT IN THE SCANNING TUNNELING MICROSCOPE, Journal of Optoelectronics and Advanced Materials Vol. 6, Iss. 1, pp. 183-188 (2004)