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HL: Fachverband Halbleiterphysik
HL 96: GaN: Growth and doping
HL 96.10: Talk
Friday, March 15, 2013, 12:00–12:15, H15
Optical properties of highly Ge doped GaN — •Christian Nenstiel1, Max Bügler1, Stephanie Fritze2, Armin Dadgar2, Hartmut Witte2, Antje Rohrbeck2, Jürgen Bläsing2, Gordon Callsen1, Alois Krost2, and Axel Hoffmann1 — 1Institut für Festkörperphysik, TU-Berlin, Hardenbergstrasse 35, 10623 Berlin, Germany — 2Institut für Experimentelle Physik, Fakultät für Naturwissenschaften
In this contribution a systematic study of highly doped GaN:Ge is presented and compared to highly doped GaN:Si. The samples were grown by MOVPE on sapphire substrates. All samples consist of AlN/AlGaN seed followed by an undoped GaN buffer layer. Subsequently, an approximately 700 nm thick doped layer was grown. The doping has been varied resulting in a variation of free carrier concentration from 8 x 10^17 to 1.9 x 10^20 cm^-3 measured by Hall-effect. The X-Ray Diffraction and Raman measurements show a high structural quality and homogeneous incorporation of Ge even at the highest doping concentration. On the Nomarski microscopy images is a smooth surface visible with just a small amount of pits. The Photoluminescence data at 7K shows a strong broadening and blue shift of the luminescence with increasing Ge content, additionally the luminescence decay time increases. The results demonstrate that free carrier concentrations up to 1.9 x 10^20 c^m-3 are achievable with Ge doping maintaining a high crystal quality.