Dresden 2020 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 57: Thin Oxides and Oxide Layers I (joint session DS/HL/O)

HL 57.4: Talk

Thursday, March 19, 2020, 10:15–10:30, CHE 91

Towards quasi two-dimensional β-Ga2O3 — •Constance Schmidt, Mahfujur Rahaman, and Dietrich R. T. Zahn — Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany

β-Ga2O3 is a transparent oxide semiconductor with outstanding properties due to its wide bandgap (Eg = 4.9 eV). It is already intensively studied in its bulk and thin film form. Studies on ultrathin films or even quasi-2D films are less common. Nevertheless, for nano electronics quasi-2D β-Ga2O3 can be beneficial as semiconductor or insulator, depending on layer thickness and doping [1]. β-Ga2O3 is not a van-der-Waals material, which makes conventional exfoliation challenging. Attempts show that layer thicknesses below 60 nm are not yet possible by exfoliating β-Ga2O3 [2]. To overcome this difficulty, we use a van-der-Waals material (GaSe), exfoliate thin flakes on Si with 300 nm SiO2, HOPG and Mica substrates, and oxidize these flakes by thermal annealing ((600 - 1000)°C, 30 min, in air) to obtain quasi 2D β-Ga2O3. In this work, we show the preparation of Se free quasi-2D β-Ga2O3 by annealing using temperatures higher than 700°C. The thin flakes obtained have thicknesses in the range of (0.5 - 50) nm as measured with atomic force microscopy. Energy dispersive X-ray spectra reveal the chemical composition of the 2D flakes and most importantly the absence of Se. Raman spectroscopy (excitation: 325 nm) verifies the β-Ga2O3 phase.

[1] J. Su, et al., J. Phys. Chem. C 122 43 24592-24599 (2018) [2] Y. Kwon, et al., APPLIED PHYSICS LETTERS 110 131901 (2017)