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Publication Citation: High-Accuracy Determination of the Dependence of the PhotoluminescenceEmission Energy on Alloy Composition in AlxGa1-xAs Films

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Author(s): Lawrence H. Robins; J T. Armstrong; Ryna B. Marinenko; Albert J. Paul; J G. Pellegrino; Kristine A. Bertness;
Title: High-Accuracy Determination of the Dependence of the PhotoluminescenceEmission Energy on Alloy Composition in AlxGa1-xAs Films
Published: April 01, 2003
Abstract: In an effort to improve the accuracy of photoluminescence (PL)spectroscopy as a composition (Al mole fraction) measurement method forthe AlxGa1-xAs alloy system, the PL peak emission energy,EPL,peak, was measured at room temperature for a set of MBE-grownAlxGa1-xAs films with Al mole fraction 0 {less than or equalto} x {less than} 0.37, and correlated with x as measured independently byin-situ reflective high-energy electron diffraction (RHEED) and also byex-situ wavelength-dispersive x-ray spectroscopy in an electronmicroprobe analyzer (WDS/EMPA). The measurement uncertainty ofEPL,peak was minimized through calibration of the photon energy scaleand spectrometer response, fitting the corrected data using a carefullychosen empirical lineshape function (asymmetric bell-curve), andmeasuring and compensating for the effect of ambient temperature drift.To enable accurate compensation of the temperature drift, a separate setof measurements was done to determine the temperature coefficientsdEPL,peak ÷ dT near room temperature. With these procedures,the 2 ς measurement uncertainty of EPL,peak was typically of theorder 5 × 10-4 eV. From correlation of the PL andWDS/EMPA results, the slope of the function EPL,peak(x) near roomtemperature was determined to be dEPL,peak ÷ dx=(1.4017 {plusor minus} 0.0090 eV)-((2.71 {plus or minus} 0.97) × 10-4eV ÷ K)(T - 298.3 K). Correlation of the PL and RHEED resultsyielded an identical slope within measurement uncertainty. Previouslypublished measurements of dEPL,peak ÷ dx are compared withthe present study. Possible reasons for the large variation in thepublished values of dEPL,peak ÷ dx are discussed. Theresults of T.F. Kuech et al. (Appl. Phys. Lett. 51, 505 (1987)), whichare based on nuclear resonant reaction analysis of the Al mole fraction,were found to be in good agreement with the present study after additionof a correction term to account for the difference in sample temperature(T=2 K for Kuech et al., T=298 K for the present study).
Citation: Journal of Applied Physics
Volume: 93
Issue: No. 7
Keywords: alloy composition,aluminum gallium arsenide,chemical composition,compound semiconductors,gallium arsenide,luminescence spectroscopy,photoluminescence,RHEED,WDS
Research Areas: Ceramics, Characterization