Regensburg 2019 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 24: Nitrides: Preparation and characterization I

HL 24.9: Talk

Wednesday, April 3, 2019, 11:45–12:00, H31

Reactive pulsed sputtering of AlN and GaN — •Florian Hörich, Christopher Kahrmann, Jürgen Bläsing, Armin Dadgar, and André Strittmatter — Otto-von-Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany

GaN based devices require high quality buffer layers difficult to achieve on Si(111) substrates. There are several limitations in common growth techniques as MOVPE growth struggles with residual Ga in the AlN nucleation layer and a high thermal mismatch between substrate and grown layer. MBE growth suffers from low lateral growth rates and a sophisticated vacuum system. Here we present a cost-effective growth technique using high purity metal targets and gases in a reactive pulsed sputter process. Plasma generation is carried out by a bipolar pulsed voltage. At negative voltages the targets are sputtered by Ar-ions whereas the positive pulse leads to a stabilisation of the target preventing the increase of an insulating nitride layer on the target. Growth of AlN and GaN on MOVPE grown AlN and GaN templates is investigated to study the process parameters. Growth pressure and gas composition impact surface morphologies of the layers as observed by AFM measurements. Below 750 °C surfaces show grainy appearance with grain sizes between 10 and 50 nm. Substrate temperatures of 750 °C lead to smoother surfaces with grain sizes up to 250 nm and improved crystal quality determined by XRD measurements. FWHM values in (002) and (103) direction reveal the same values for the grown layer and the MOVPE grown templates.