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HL: Fachverband Halbleiterphysik
HL 81: Focus Session: Extended defects in semi- and nonpolar GaN II
HL 81.3: Talk
Thursday, March 14, 2013, 15:15–15:30, H13
Comparative study on Si and Ge doping in a- and c-plane GaN — •Matthias Wieneke1, Hartmut Witte1, Stephanie Fritze1,2, Armin Dadgar1, Jürgen Bläsing1, and Alois Krost1 — 1Otto-von-Guericke-Universität Magdeburg, FNW/IEP, Universitätsplatz 2, 39106 Magdeburg — 2present address: LayTec AG, Seesener Str. 10-13, 10709 Berlin
The doping efficiencies of Si and Ge were studied by simultaneous growth of n-type doped a-plane and c-plane GaN. For this purpose undoped a-plane and c-plane GaN templates were grown by low pressure metal-organic vapor phase epitaxy (MOVPE) on 2 inch r-plane and c-plane sapphire substrates, respectively. After cleaving into half wafers one template of each orientation was re-loaded into the MOVPE system. Thus, in each case the Si- and Ge-doped GaN layers were grown at identical conditions on the a-plane and c-plane GaN templates using trimethylgallium (TMGa), ammonia (NH3), silane (SiH4) and germane (GeH4) as precursors. The electrical properties of the undoped templates and the doped GaN layers were investigated by conductivity and Hall-effect measurements. By doping with germane the electron concentration in nonpolar a-plane GaN is typically about 50 times higher than in c-plane GaN, while it is nearly identical when using silane doping. Thus, the Ge incorporation is drastically enhanced in the case of a-plane GaN and is consequently strongly dependent on the crystal orientation of the GaN. In our contribution we will discuss possible origins of the different doping efficiencies.