SKM 2023 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 51: Nitrides: Preparation and Characterization

HL 51.7: Talk

Friday, March 31, 2023, 11:15–11:30, POT 112

Growth of ScN and AlScN by reactive sputter epitaxy — •Florian Hörich, Christopher Lüttich, Ralf Borgmann, Jürgen Bläsing, André Strittmatter, and Armin Dadgar — Otto-von-Guericke University

Spontaneous polarization fields induced by a strained AlGaN/GaN layer structure lead to high-density two-dimensional electron gases which are key to current high-power and high-frequency transistor devices. Recent theoretical and experimental data demonstrated an even higher two-dimensional electron density when AlScN is used [1 ]. Up to now, growth of Sc-containing materials by conventional MOVPE is hampered by the lack of a suitable Sc precursor. Reactive sputter epitaxy using metallic Al and Sc targets together with ammonia or molecular nitrogen has the potential to fabricate high quality layers at low cost. We will discuss principle growth parameters such as temperature and nucleation conditions for ScN and AlScN on bare Si(111) substrates and on MOVPE grown GaN templates. A large impact of growth temperature is observed on crystal structure and surface morphology. Single-phase crystalline material is obtained at temperatures > 800 °C. We find different optimum nucleation conditions for both kind of substrate surfaces. Growth on bare Si(111) surfaces with an initial metallic Sc thickness equivalent to <1 nm drastically improves crystallinity. For the GaN(0001) template surface, such sequence has no impact. Additionally, sputtering of AlScN and ScN with ammonia results in better structural quality than with nitrogen.

[1] I. Streicher, et. al. Phys. Status Solidi RRL 2200387