Regensburg 2013 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 96: GaN: Growth and doping

HL 96.9: Vortrag

Freitag, 15. März 2013, 11:45–12:00, H15

Influence of Si- and Ge-doping on the properties of AlGaN layers — •Christoph Berger, Hartmut Witte, Armin Dadgar, Jürgen Bläsing, Peter Veit, Annette Diez, and Alois Krost — Otto-von-Guericke-Universität Magdeburg, Institut für Experimentelle Physik, Magdeburg

We investigate n-doping of Al_0.2Ga_0.8 layers using silane and germane as dopants. For this purpose doped AlGaN films with thicknesses of about 400 nm were grown on an undoped Al_0.2Ga_0.8-buffer. With both dopant sources, it was possible to achieve electron concentrations of nearly 10²⁰ cm⁻³ as determined by Hall-effect measurements. However, when doping was applied, an increase in tensile stress was observed by means of in-situ curvature measurements. This effect becomes more pronounced at higher dopant fluxes and higher dislocation densities of the buffer. For Si-doping this effect is similar to GaN, where Si-doping is known to lead to dislocation climb. On the contrary, it can be shown that for Ge-doping the tensile stress is caused by a change in alloy composition as determined by X-ray diffraction. With higher Ge-fluxes, the Al-concentration of the film increases, consequently the Ge-doped film grows tensely strained on the buffer. Interestingly, the influence on the composition also depends on the dislocation density.