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HL: Fachverband Halbleiterphysik

HL 22: Heterostructures, Interfaces and Surfaces

HL 22.9: Vortrag

Mittwoch, 7. September 2022, 17:30–17:45, H33

Growth of epitaxial GaN by reactive magnetron sputtering — •Ralf Borgmann, Florian Hörich, Jürgen Bläsing, Armin Dadgar, André Strittmatter, Anja Dempewolf, Frank Bertram, Jürgen Christen, and Gordon Schmidt — Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany

For high power transistors GaN is an excellent base material semiconductor with a high bandgap and a high breakdown field which is often realized on Si substrates. A specific buffer arrangement is needed for MOVPE grown structures, to achieve these properties. Especially doping with Fe or C is essential for insulating sheets. In comparison with reactive magnetron sputtering uses pure metal targets and does not necessarily require Fe or C doping to achieve highly insulating GaN. We investigated growth parameters like growth temperature and reactive gas flow on various templates. An important parameter determining the material quality is the reactive gas. Ga droplets occur on the wafer surface, when using nitrogen. Investigations on growth temperature reveal a narrow growth window. An optimum growth temperature was by around 715 °C. With low ammonia gas flow the AFM measurement shows a grainy surface. By using a higher ammonia gas flow, the growth rate decreases and a closed meandering surface structure appears. Full sputtered undoped layers show a vertical breakdown field strength of > 2.5 MV/cm for 200 nm AlN 2x 200 nm transition layer AlGaN and 820 nm GaN.