Berlin 2005 – scientific programme

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HL: Halbleiterphysik

HL 5: Grenz- und Oberfl
ächen

HL 5.4: Talk

Friday, March 4, 2005, 11:30–11:45, TU P-N202

Band alignment in CuIn₅S₈ / CuI heterostructures — •Igor Konovalov, Liudmila Makhova, and Rüdiger Szargan — Universität Leipzig, Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Linnéstr. 2, 04103 Leipzig

Being a typical n-type semiconductor, CuIn₅S₈ spinel has a band gap of 1.5 eV. We studied the valence band alignment at the interface between CuIn₅S₈ and the typical p-type transparent semiconductor CuI using X-ray photoelectron spectroscopy. Single crystalline CuIn₅S₈ was cleaved in-situ and CuI sublimating from a Knudsen cell at 360 ^∘C resulted in a deposition rate of 0.3 Å/min. The band discontinuity was found to include a minor cliff for the minority holes of about 0.1 eV. In non-epitaxial heterojunctions, band alignment with a cliff generally enhances the interface recombination current mechanism through the junction due to the narrowing of the band gap at the interface for the cross-interface recombination involving the interface states. However, the cliff height found here is significantly smaller than that observed in AgIn₅S₈ / CuI heterojunctions before. This trend is in correspondence with the larger band gap of AgIn₅S₈ and with the doping pinning rule in its application to sulfidic semiconductors close to the equillibrium.