Semiconducting hydridesS. Zh. Karazhanov1, 2, A. G. Ulyashin3, P. Ravindran1 and P. Vajeeston1
1 Center for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo P.O. Box 1033, Blindern, N-0315 Oslo, Norway
2 Physical-Technical Institute - 2B Mavlyanov St., 700084 Tashkent, Uzbekistan
3 Institute for Energy Technology - P.O. Box 40, NO-2027 Kjeller, Norway
received 13 November 2007; accepted in final form 6 February 2008; published April 2008
published online 11 March 2008
Using first-principles density functional calculations with AlH3, KMgH3, LiMgH3, NaBeH3, NaMgH3, and RbMgH3 as model systems we have analyzed the band structure of hydrides. It is shown that hydrides can possess the features of semiconductors with n- and/or p-type electrical conductivity. We have found that carrier effective masses of some hydrides are almost the same as those of commonly known semiconductors. The present study suggests that the Mg impurities substituting Al form a shallow acceptor level in the band gap of AlH3, which can provide holes and cause p-type electrical conductivity. From studies of optical properties we have found that even if Mg impurities of about 1.31021 cm-3 concentration substitute the Al site, AlH3 can still be transparent in the visible spectra. This result opens up the door for the application of hydrides in the future generation of optoelectronic devices.
71.20.-b - Electron density of states and band structure of crystalline solids.
71.55.-i - Impurity and defect levels.
71.15.Mb - Density functional theory, local density approximation, gradient and other corrections.
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