Berlin 2015 – wissenschaftliches Programm
HL 96.18: Poster
Donnerstag, 19. März 2015, 14:00–20:00, Poster B
Photoluminescence of Si-doped AlxGa1−xN with aluminum mole fractions beyond 80% — •Dimitri Henning, Christoph Reich, Frank Mehnke, Tim Wernicke, Christian Kuhn, Harald Pingel, and Michael Kneissl — Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany
For the realization of deep ultraviolet light emitting diodes, highly conductive n-doped layers are needed. In this study we investigate the photoluminescence of Si-doped doped n-AlxGa1−xN (0.8<x<1) layers grown by metal organic vapor phase epitaxy on epitaxially laterally overgrown AlN/sapphire templates. We found the resistivity is highly dependent on the SiH4/III ratio leading to a narrow growth window. Si-doped n-AlxGa1−xN layers with resistivites as low as 0.026 Ω cm have been realized. The n-AlGaN layers were excited by an ArF-excimer laser (193 nm) in a range between 5 K-300 K. Low temperature PL spectra show near band gap emission as well as different defect bands depending on the SiH4/III ratio. Three major defect luminescence bands were identified as impurity transitions using assignments from literature as (VIII-complex)1−, (VIII-complex)2−, (VIII)3− (listed high to low energy position). For SiH4/III ratio below the optimum condition the emission related to the (VIII-complex)1− appears to be the strongest defect luminescence band. At the optimum condition intensity of all defect luminescence bands reaches a minimum in comparison to the band edge luminescence. A higher SiH4/III ratio leads to a strong increase of (VIII)3− related defect luminescence.