Hall Effect Studies of AlGaAs Grown by Liquid Phase Epitaxy for Tandem Solar Cell Applications
Xin Zhao, Kyle H. Montgomery, and Jerry M. Woodall
Journal of Electronic Materials, Aug. 2014.
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We report results from Hall effect studies on AlxGa1xAs (x = 0.23–0.24) with bandgap energies of 1.76 ± 0.01 eV grown by liquid-phase epitaxy (LPE). Room-temperature Hall measurements on unintentionally doped AlGaAs revealed p-type background doping for concentrations in the range 3.7–5.2 9 1016 cm3. Sn, Te, Ge, and Zn-doped AlGaAs were also characterized to study the relationship between doping concentrations and the atomic fractions of the dopants in the melt. Temperature-dependent Hall measurements were performed to determine the activation energies of the four dopants. Deep donor levels (DX centers) were dominant for Sn-doped Al0.24Ga0.76As, but not for Te-doped Al0.24Ga0.76As. Comparison of the temperature-dependent Hall effect results for unintentionally and intentionally doped Al0.24Ga0.76As indicated that the impurity contributing to the p-type background doping had the same activation energy as Mg. We thus suggest a Te-doped emitter and an undoped or Ge-doped base to maximize the efficiency of AlxGa1xAs (x 0.23) solar cells grown by LPE.
AlGaAs, liquid-phase epitaxy, Hall effect, doping, tandem solar cell
X. Zhao, K. H. Montgomery, and J. M. Woodall, “Hall Effect Studies of AlGaAs Grown by Liquid Phase Epitaxy for Tandem Solar Cell Applications,” J. Electron. Mater., vol. 43, no. 11, pp. 3999-4002, Nov. 2014.