Berlin 2008 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 55: GaN: preparation and characterization II
HL 55.7: Talk
Friday, February 29, 2008, 12:15–12:30, ER 164
Luminescence Characterization of GaN/InGaN Micro-disk Structures on Silicon — •A. Franke1, F. Bertram1, J. Christen1, A. Dadgar1,2, A. Krost1,2, K. X. Lin3, S.L. Teo3, and S. Tripathy3 — 1Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Germany — 2Azzurro Semiconductors AG, Magdeburg, Germany — 3Institute of Material Research and Engineering, Singapore 117602
The most common way to fabricate vertical surface emitting lasers like micro-cavities lasers uses DBRs on both sides of the cavity. An alternative approach to achieve an optical confinement is the fabrication of free standing micro-disk emitters. The investigated micro-disk sample consists of a standard MOVPE grown GaN LED structure with InGaN quantum wells as the active region. The 3 µm thick structure was patterned into 300 µm circular columns using dry and subsequently wet etching to remove and undercut the silicon surrounding the micro-disk. To investigate the optical properties we use micro-photoluminescence (PL) and cathodoluminescence spectroscopy at 4 K. The local spectra exhibit two emission peaks: a dominant emission at 2.66 eV related to the InGaN/GaN QWL and at 3.46 eV stemming from the GaN emission. PL mapping across the surface of the disk shows a statistical distribution for the GaN emission. In contrast, for the QWL emission a symmetric circular pattern with a 5 – fold symmetry of alternating 2.69 eV emission interrupted by a 2.66 eV emission can be observed.