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HL: Fachverband Halbleiterphysik
HL 34: Poster I: III-V Semiconductors
HL 34.26: Poster
Tuesday, March 23, 2010, 18:30–20:30, Poster D2
Cathodoluminescence on heteroepitaxial grown a-plane GaN - reduction of the BSF-luminescence — •Martin Noltemeyer, Matthias Wieneke, Thomas Hempel, Armin Dadgar, Jürgen Bläsing, Alois Krost, and Jürgen Christen — Otto-von-Guericke-Univeristy Magdeburg, Germany
Until now heteroepitaxially grown a-plane GaN films have a high density of structural defects (basal plane stacking faults - BSF) that causes a luminescence-line at about λ = 362 nm. We present a Si-doped a-plane GaN film, grown on r-sapphire with a high temperature AlGaN nucleation layer without an evidence of basal plane stacking faults in x-ray diffraction measurements. Using highly spatially and spectrally resolved cathodoluminescence spectroscopy (CL) the Si doped, heteroepitaxially grown a-plane GaN sample was analyzed. Low temperature (T = 5.2 K) CL spectra, integral as well as local spectra of the three dimensionally grown crystallites, are dominated by the near band edge emission and have a comparatively weak intensity at the spectral region of the BSF-luminescence (λBSF = 362 nm). The broadening of the spectra, caused by the Si-doping, with a full width at half maximum of 105 meV is, following [1], appreciated to an impurity concentration (ND+NA) of about n = 3 · 1019 cm−3. In addition, the defect-luminescence intensity in the yellow spectral region (around λ = 550 nm) is very weak compared to the near band edge emission which indicates a good crystalline quality. [1] E.F. Schubert, I.D. Goepfert, W. Grieshaber, J.M. Redwing, Appl. Phys. Lett. Vol. 71, No. 7 (1997)