Persistent photoconductivity in p-type ZnO(N) grown by molecular beam epitaxy.

Authors :: Polyakov, A. Y.
Smirnov, N. B.
Govorkov, A. V.
Belogorokhov, A. I.
Kozhukhova, E. A.
Markov, A. V.
Osinsky, A.
Dong, J. W.
Pearton, S. J.
Source :: Applied Physics Letters; 3/26/2007, Vol. 90 Issue 13, p132103-1, 3p, 1 Chart, 4 Graphs
Publication Year :: 2007
Abstract: Current transport mechanisms and persistent photoconductivity effects were studied in nitrogen-doped ZnO films grown by molecular beam epitaxy having p-type or n-type conductivity at 25 °C. In both types of samples the current flow is determined by the n-type channels surrounded by higher resistivity regions. The persistent photoconductivity wave form is reasonably described by the stretched-exponents-type expression, with only a slight temperature dependence of the characteristic decay time. The persistent photocurrent decay process is greatly accelerated by infrared illumination (threshold energy of the photons ∼1.4 eV). The results suggest that the Fermi level in the higher resistivity regions is pinned near E<subscript>v</subscript>+1.9±0.1 eV and the height of the potential barrier for electrons in the n-type channels is around 1.4±0.1 eV. [ABSTRACT FROM AUTHOR]