Real-time optical techniques and QMS to characterize growth in a modified commercial OMVPE reactor

Reciprocal-space analysis offers several advantages for determining critical point parameters in optical and other spectra, for example the separation of baseline effects, information, and noise in low-, medium-, and high-index Fourier coefficients, respectively. However, endpoint-discontinuity artifacts can obscure much of the information when segments are isolated for analysis. We developed a procedure for eliminating these artifacts and recovering buried information by minimizing in the white-noise region the mean-square deviation between the Fourier coefficients of the data and those of low-order polynomials, then subtracting the resulting coefficients from the data over the entire range. We find that spectral analysis is optimized if no false data are used, i.e., when the number of points transformed equals the number of actual data points in the segment. Using fractional differentiation we develop a simple derivation of the variation of the reciprocal-space coefficients with index n for Lorentzian and Gaussian line shapes in direct space. More generally, we show that the definition of critical point energies in terms of phase coherence of the Fourier coefficients allows these energies to be determined for a broad class of line shapes even if the direct-space line shapes themselves are not known. Limitations for undersampled or highly broadened spectra are discussed, along with extensions to two- or higher-dimensional arrays of data.

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Real-time optical techniques and QMS to characterize growth in a modified commercial OMVPE reactor

Cited by 5 publications

References 33 publications

III–V Epitaxy, Monitoring and Closed-Loop Feedback Control of Spectroscopic Ellipsometry of

III–V Epitaxy, Monitoring and Closed-Loop Feedback Control of Spectroscopic Ellipsometry of

The metal-organic chemical vapor deposition and properties of III–V antimony-based semiconductor materials

Elimination of endpoint-discontinuity artifacts in the analysis of spectra in reciprocal space

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