Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 81: Heterostructures and interfaces

HL 81.5: Vortrag

Donnerstag, 19. März 2015, 16:00–16:15, EW 201

An XPS study on copper oxide based solar cells — •Benedikt Kramm, Philipp Hering, Philipp Schurig, Fabian Michel, Angelika Polity, and Bruno K. Meyer — 1. Physikalisches Institut, Justus-Liebig-Universität, Heinrich-Buff-Ring 16, 35392 Gießen

For semiconductor hetero junctions the energy band alignment is one of the crucial factors which deliver a judgment for a successful operating device. We fabricated hetero junctions based on p-type cuprous oxide with n-type Al_xGa_1−xN (first type) and Mg_xZn_1−xO (second type) as window layer. The Al_xGa_1−xN film was grown epitaxial on sapphire substrates whereas the copper oxide was deposited on top by RF-magnetron sputtering. Mg_xZn_1−xO was similar deposited on sapphire substrates by RF-magnetron sputtering and again finally Cu₂O was deposited. An advantage of Mg_xZn_1−xO compared to Al_xGa_1−xN is the low cost fabrication even on a large scale as well as the sustainability of the elements. But it is well known that Mg_xZn_1−xO has its limits in conductivity with increasing Mg content. Nevertheless, it might be possible to align the conduction bands of Mg_xZn_1−xO/Cu₂O hetero junctions and thus to force up the efficiency in power conversion. Using X-ray photoelectron spectroscopy (XPS), we figured out that the conduction band offsets are getting smaller with increasing Al content for the first type of hetero structures. A similar trend is observable for Mg in the second type. Here, we will present and compare the band offset results. Another focus is on the intermixing at the oxygen-nitrogen and oxygen-oxygen interfaces and how it affects the band alignment.