Regensburg 2007 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 42: GaN: devices

HL 42.2: Talk

Thursday, March 29, 2007, 14:15–14:30, H13

Electrical properties of nonpolar cubic Al_xGa_1−xN/GaN HFETs — Stefan Potthast¹, •Marcio Peron Franco de Godoy¹, Elena Tschumak¹, Jörg Schörmann¹, Donat Josef As¹, Klaus Lischka¹, Hiroyuki Nagasawa², and Masayuki Abe² — ¹Universität Paderborn, Department Physik, Warburger Strasse 100, 33095 Paderborn, Germany — ²HOYA SiC Developement Center, Ltd, 1-17-16 Tanashioda, Sagamihara,Kanagawa 229-1125, Japan

Since polarization fields can limit the performance of heterojunction field-effect transistors (HFETs) some attention has been focused recently on the growth of wurtzite structures with nonpolar orientations e.g., growth along a, m or R directions and also on cubic nitrides. In this contribution we report on the growth of cubic Al_xGa_1−xN/GaN HFET structures by radio-frequency plasma assisted molecular beam epitaxy on 3C-SiC substrates with an Al-mole fraction between 0.2 and 0.5. The Mesa structures were realized using reactive ion etching technique. The source and drain contacts were deposited by thermal evaporation using 200 nm thick pure In as contact material. The gate contact was formed by thermal evaporation using Ni as Schottky contact material with a thickness of 50 nm. Analysis of capacity voltage characteristics at T=150 K reveal a clear evidence for the existence of the two-dimensional electron gas. A sheet carrier concentration of 1.6x10¹² cm⁻² is measured at the interface. The source-drain current-voltage characteristics measured at 150 K exhibited a clear field effect induced by the gate voltage.