SKM 2023 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 6: Poster
KFM 6.46: Poster
Dienstag, 28. März 2023, 17:00–19:00, P3
Temperature dependence of the optical band gap of LNT solid solutions (20–330 K) — •T. Hehemann1, A. Pfannstiel1, S. Sanna2, N. Syvorotka3, K.-D. Becker4, S. Ganschow5, and M. Imlau1 — 1Inst. Phys., Osnabrück Univ. — 2Inst. Phys., Univ. Giessen — 3Inst. Energy Res., TU Clausthal — 4Inst. Phys. Theo. Chem., TU Braunschweig — 5Leibniz-Inst. f. Kristallzüchtung, Berlin
Lithium niobate tantalate solid solutions (LNT, LiNbxTa1−xO3 with 0≤x≤1) represent a promising class of polar oxide materials for photonics due to their favourable linear & nonlinear optical, but also photoelectrical properties. A mandatory basic requirement for customised optical applications is the (precise) knowledge of the optical band edge energy Egapopt. While Egapopt and its relation to the intrinsic defect structure has been well investigated for the edge compositions LiNbO3 (LN, x=1) and LiTaO3 (LT, x=0), nearly nothing is reported for LNT in literature, so far. In particular, there are no data available for the important low temperature region 20–330 K. We here present temperature dependent absorption spectra of LNT in the vicinity of the optical band edge covering the entire composition range (0≤x≤1). The analysis of the data set follows the established fitting routines and reveals, both the composition and temperature dependent shifts of Egapopt(x,T). The former is discussed in the framework of the intrinsic defect structure, while the latter is related with the properties of the electronic structure. All findings are compared with respective shifts widely reported for LN and LT. Financial support by the DFG (projects IM 37/12-1, SA 1948/3-1, FR 1301/40-1, GA 2403/7-1 of the FOR 5044)