Regensburg 2025 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 46: Optical Properties

HL 46.8: Talk

Thursday, March 20, 2025, 12:00–12:15, H15

Investigation of PLD-grown β-CuI — •Aaron Gieß, Lukas Trefflich, Gabrielle Benndorf, Marius Grundmann, and Chris Sturm — Universität Leipzig, Felix-Bloch-Institut für Festkörperphysik, Germany

Copper iodide (CuI) is a transparent semiconductor that is currently of great interest due to its inherent p-type behavior and its high exciton binding energy of 62 meV. Typically, CuI crystallizes in the zincblende structure (γ-CuI) at room temperature. However, CuI can also crystallize in other phases, which are thermodynamically not stable at ambient pressure and temperature. One of these phases is the rhombohedral phase, which is often also called β-phase. Under certain growth conditions, this β-phase appears simultaneously with the γ-phase.

We grew closed thin films of CuI on c-sapphire, using pulsed laser deposition. The influence of the growth-parameters on the occurrence of β-CuI seems to be a multidimensional problem. The most important parameter is the film thickness, with thinner films favouring a higher fraction of the β-phase. The appearance of the β-phase causes additional features in the 2θ-ω scan in XRD, the dielectric function and the optical transmittance. Furthermore, photoluminescence spectra reveal a change of the emission spectra with time, which indicates that a photobleaching processes takes place.

Keywords: copper iode; pulsed laser deposition; photoluminescense; beta phase; photobleaching