GaPN on Si 100 and buried interfaces

Renewable and e amp; 64259;cient generation of hydrogen is one of the key challenges towards a society being independent from fossil fuels. Tandem absorber structures based on dilute nitride GaPN Si 100 are promising candidates regarding hydrogen evolution by direct solar water splitting. Their production by metalorganic vapor phase epitaxy MOVPE is challenging, particularly regarding speci amp; 64257;c preparation of the interfaces. Due to the small lattice mismatch, GaP Si 100 structures are suitable as quasisubstrates for further integration of III V semiconductors. In the present work, the atomic order of Si 100 and GaP N Si 100 surfaces, as well as of the buried GaP Si 100 heterointerface is studied in situ with re amp; 64258;ection anisotropy spectroscopy RAS . RAS results are benchmarked to results from complementary surface science techniques in ultrahigh vacuum UHV , such as low energy electron di amp; 64256;raction LEED and X ray photoelectron spectroscopy XPS . Preparation of almost single domain dimerized Si 100 surfaces succeeds in MOVPE ambient containing Ga, P background residuals and can be controlled in situ with RAS. The sublattice orientation of the GaP films can thereby be selected i via the dimer orientation on the Si substrate, ii via the Ga,P chemical potential during nucleation, or iii via modification of the Si surface with As. Correlating time resolved RAS and XPS measurements as well as density functional theory calculations, for typical process conditions it can be concluded on a kinetically limited formation of a Si P interface. Subsequent to a GaP nucleation layer, which is only few atomic layers thick, GaPN Si 100 surfaces free of antiphase disorder can be prepared. These reconstruct in analogy to GaP Si 100 surfaces if excess N is avoide