Raman Scattering Determination Of Carrier Concentration And Surface Space Charge Layer IN <100> n-GaAs

H. Shen; Fred H. Pollak; R. N. Sacks

doi:10.1117/12.946331

28 June 1985 Raman Scattering Determination Of Carrier Concentration And Surface Space Charge Layer IN <100> n-GaAs

H. Shen, Fred H. Pollak, R. N. Sacks

Proceedings Volume 0524, Spectroscopic Characterization Techniques for Semiconductor Technology II; (1985) https://doi.org/10.1117/12.946331
Event: 1985 Los Angeles Technical Symposium, 1985, Los Angeles, United States

Abstract

We have used Raman scattering as a non-destructive, contactless method for determining the width of the space charge layer as well as the bulk free carrier concentration, N, from 4100). n-GaAs. In the general case, for optical penetration depths larger than the depletion widths, the Raman spectra will show the peak of the coupled plasmon-LO phonon modes from the bulk (14, L_) as well as the uncoupled LO phonon mode from the depletion layer. The intensity of this latter feature is dependent on the relation between the width of the layer, Ls, and the penetration depth of the incident light. We have investigated the room temperature Raman spectra in the backscattering configuration from a number of <100> n-GaAs (Si-doped) samples with 4 x 101/ cm-1(N<1 x 101 cm using as an excitation several different wavelengths of an At laser. From the position of the L.f., L- modes, we have determined the bulk carrier concentration, N. By comparing the intensity at different wavelengths of the uncoupled LO mode originating in the space charge layer with the signal from a piece of undoped4C100), material, it is possible to experimentally evaluate Ls. We find that there is very good agreement between the experimental values and those obtained from a generalized theory for both degenerate and non-degenerate materials. Thus, these experimental results demonstrate that for <100),III-V semiconductors, not only can Raman scattering be used as a contactless method for evaluating N, but also to determine the width of the space charge region for carrier concentrations up to 1 x 10 19 cm -3

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H. Shen, Fred H. Pollak, and R. N. Sacks "Raman Scattering Determination Of Carrier Concentration And Surface Space Charge Layer IN <100> n-GaAs", Proc. SPIE 0524, Spectroscopic Characterization Techniques for Semiconductor Technology II, (28 June 1985); https://doi.org/10.1117/12.946331

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