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Photoreflectance Study of the Chemically Modified (100) GaAs Surface



John A. Dagata, O Glembocki, J Tuchman, K Ko, S Pang


Photoreflectance (PR) spectroscopy has been used to study the Fermi-level pinning position of chemically modified (100) GaAs surfaces. It is shown that there are two pinning positions for the unmodified (100) GaAs surface. For n-GaAs, the Fermi level pins near midgap, while for p-GaAs the Fermi level pins near the valence band. We used an Ar/Cl(2) plasma generated by an electron-cyclotron resonance (ECR) source and P2S5 chemical passivation to change the stoichiometry of the surface. We show that ECR etching makes the surface oxide As rich and that the Fermi-level position for this circumstance is near midgap. The P(2)S(5) passivation produces a thin Ga rich oxide which is observed to pin the Fermi-level near the valence band. These results allow us to relate the Fermi-level pinning position to the stoichiometry of the GaAs/oxide interface.
Proceedings Title
Proceedings of SPIE
Conference Dates
January 26, 1994
Conference Location
Los Angeles, CA, USA
Conference Title
Spectroscopic Characterization Techniques for Semiconductor Technology V, Orest J. Glembocki, Editor May 1994, Semiconductor Device Characterization I


Dagata, J. , Glembocki, O. , Tuchman, J. , Ko, K. and Pang, S. (1994), Photoreflectance Study of the Chemically Modified (100) GaAs Surface, Proceedings of SPIE, Los Angeles, CA, USA (Accessed May 28, 2024)


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Created April 30, 1994, Updated October 12, 2021