Electrochemical Passivation of Homoepitaxial InP (100) Thin Films for Light Induced Hydrogen Evolution: A Synchrotron Radiation Photoelectron Spectroscopy Study

Autor:	Hagen W. Klemm, N. Szabó, Christian Heine, Hans-Joachim Lewerenz, A.G. Muñoz, Thomas Hannappel
Rok vydání:	2011
Předmět:	chemistry.chemical_compound Materials science Passivation chemistry Band gap Analytical chemistry Oxide Metalorganic vapour phase epitaxy Thin film Conductivity Electrochemistry Ultraviolet photoelectron spectroscopy
Zdroj:	ECS Transactions. 35:141-150
ISSN:	1938-6737 1938-5862
DOI:	10.1149/1.3567746
Popis:	Recent synchrotron radiation photoelectron spectroscopy (SRPES) investigations on the surface chemistry of electrochemically conditioned surfaces of homo-epitaxial p-InP(100) layers deposited by MOVPE are described. The electrochemical conditioning, consisting in a voltammetric cycling in an HCl solution under illumination and a subsequent photo-electrochemical deposition of Rh, yields efficient photoelectrodes for light induced hydrogen evolution. The deconvolution of the In 3d5/2 and P 2p lines reveals that the oxide film consists of InPO3, In2(PO3)3 and In2O3. The presence of In2O3, with a band gap of 2.6 eV and an affinity of 4.3 eV can explain the conductivity of the oxide film, of about 7 nm thickness, by resonance tunneling. The detection of minute amounts of adsorbed Cl-atoms, presumably at the InP-oxide interface, is in agreement with the formation of interfacial dipoles responsible for the photoelectrochemical activation as confirmed by ultraviolet photoelectron spectroscopy (UPS)-measurements.
Databáze:	OpenAIRE
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