Regensburg 2004 – scientific programme

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HL: Halbleiterphysik

HL 24: Photovoltaik I

HL 24.1: Talk

Tuesday, March 9, 2004, 17:45–18:00, H15

Doping experiments with HfS_xSe_2−x — •Steffen Duhm, Ralf Severin, Alicia Krapf, Christoph Janowitz, and Recardo Manzke — Institut f. Physik, Humboldt-Unversität zu Berlin, Newtonstr. 15, 12489 Berlin

HfS_xSe_2−x is an indirect semiconductor of the group of transition metal dichalcogenides, the band-gap of which ranges from 1.1 eV (HfS₂) to 2 eV (HfSe₂) with a nearly linear dependence on x. Due to this property it can be used as a source material for a two junction cell (ideal band-gap 1.1 eV and 1.8 eV). In the present work, niobium doped HfS₁Se₁ (band-gap ∼ 1.5 eV) crystals with different doping concentrations were grown by chemical vapour transport (CVT). The crystals were characterized by energy dispersive X-ray analysis (EDX) and absorption measurements. Despite the indirect band-gap of HfS_xSe_2−x the absorption coefficient is very high and enables thin-film solar cells. The quasi two-dimensional character of HfS_xSe_2−x prevents surface states and dangling bonds. As the material is thus highly suitable for a Schottky contact, the work function was measured using a Kelvin probe.