AlInP Benchmarks for Growth of AlGaInP Compounds by Organometallic Vapor-Phase Epitaxy

We have demonstrated that source material and growth system purity can be successfully evaluated by characterizing AlInP samples grown by organometallic vapor-phase epitaxy with photocurrent versus voltage measurements in an electrochemical cell. The samples can be grown and characterized in about 1 h, making them well-suited for system benchmarks. Zn-doped AlInP has the greatest sensitivity for O contamination, a recurring problem in the growth of AlGaInP alloys. High O concentrations in the Zn-doped benchmarks cause the photoresponse to fall dramatically. Secondary ion mass spectrometry data are consistent with compensation of Zn acceptor states by O donor-like trap states. Photocurrents of Si-doped and Se-doped AlInP are less sensitive to the O contamination, and the behavior of these n-type samples suggests that multiple energy states can be associated with the O impurities and dopant atoms. The benchmarks have been used to identify O contamination in trimethyl indium and phosphine and to evaluate new growth systems. Application of the benchmark to growth of GaInP solar cells with AlInP window layers is also discussed. Published by Elsevier Science B.V.