Regensburg 2007 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 15: Poster Session
DS 15.42: Poster
Dienstag, 27. März 2007, 15:00–17:00, Poster B
Band Bending Investigation of Ag/S-GaAs(100) Schottky Contacts by Raman Spectroscopy — •Steve Pittner and Dietrich Zahn — Chemnitz University of Technology, Semiconductor Physics, D-09107 Chemnitz, Germany
Raman spectroscopy is a powerful tool to study in situ the growth processes of Schottky contacts [1]. It also can be used to determine band bending changes in GaAs [1].
In this investigation the band bending changes of n-and p-doped GaAs are monitored a sulfur passivation with a S2Cl2 + CCl4 (1:3) solution during the formation of a Ag/S-GaAs Schottky contact. The sulfur passivation changes the position of acceptor and donator levels in the band gap and the deposition of Ag on S-GaAs creates metal induced gap stats (MIGS) within the gap. The new charge distribution at the surface leads to change in the width of the depletion layer. This yields a change of the intensity of the longitudinal-optical phonon (LO-Phonon) in the depletion layer and the coupled Plasmon-LO-Phonon (PLP) mode in the bulk of GaAs. Thus the band bending can be calculated, using the ratio of both elementary Raman excitations [2].
This technique was used to determine the band bending induced by the sulfur passivation and the subsequent annealing process as by well as the formation of a Ag/GaAs Schottky contact for both n- and p-doped GaAs substrates.
[1] Salvan G., PhD. Thesis TU Chemnitz (2003)
[2] Geurts J. , Surf. Sci. Rep., 18, (1993), 1