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Published July 1986 | public
Journal Article Open

Current transport mechanisms in GaAs/AlAs tunnel structures grown by metal–organic chemical vapor deposition

Abstract

Elastic and inelastic tunneling processes are investigated in GaAs–AlAs–GaAs double heterojunctions grown in the [100] direction by metal–organic chemical vapor deposition (MOCVD). The AlAs quantum barriers in the heterostructures studied are doped p-type with Mg. Theoretical calculations of tunneling currents are performed and compared with experimental I–V data. It is found that for structures with thin AlAs barriers, the dominant current transport mechanism at low temperatures is tunneling through the AlAs band gap at both the Gamma and X points. This is consistent with inelastic processes observable in first (dI/dV) and second (d2I/dV2) derivative spectra obtained with modulation techniques. A simple model, developed for calculating impurity-assisted tunneling currents, shows that the role of barrier impurities becomes more important as the barrier is grown thicker. Implications of some of these results for resonant tunneling heterostructures consisting of two AlAs quantum barriers separated by a GaAs quantum well are discussed. Experimental second derivative spectra showing reproducible features are also presented for these double barrier structures.

Additional Information

© 1986 American Vacuum Society (Received 5 March 1986; accepted 7 April 1986) The authors wish to acknowledge R. S. Bauer, C. Mailhiot, R. H. Hauenstein, R. H. Miles, T. K. Woodward, and G. Y. Wu for valuable discussions, and are grateful to H. F. Chung, F. Endicott, D. M. Taylor, T. T. Tjoe, T. Anderson, J. Tramontana, W. Mosby, D. W. Treat, and F. E. Nelson for technical assistance. This work was supported in part by the Defense Advanced Research Agency under Contract No. N000014-84-C-0083 and the Office of Naval Research under Contract No. N00014-82-K-0556.

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