Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 56: GaN: Optical characterization
HL 56.3: Vortrag
Mittwoch, 13. März 2013, 12:30–12:45, H15
Temperature-dependent external quantum efficiencies of bulk ZnO and GaN — •Nils Rosemann1, Melanie Pinnisch2, Stefan Lautenschläger2, Martin Eickhoff2, Bruno K. Meyer2, and Sangam Chatterjee1 — 1Fachbereich Physik, Philipps-Universität Marburg, Renthof 5, D-35032 Marburg, Germany — 2I. Physikalisches Institut, Justus-Liebig-University Gießen, Heinrich Buff-Ring 16, 35392 Gießen, Germany
The most promising candidates for efficient solid-state UV-emitters today are probably those based on GaN. Nevertheless, ZnO has to be taken into account as an alternative material as these two materials share many physical properties such as large band-gap, exciton binding energies and a wurtzite crystal structure. However, both of them have their respective down-sides. In case of GaN the realization of high power devices remains the largest challenge, whereas ZnO still lacks the possibility of efficient and controllable p-type doping. To quantify the potential of both materials we investigate two series of GaN and ZnO bulk layers by temperature-dependent absolute photoluminescence spectroscopy using an integrating sphere mounted inside a cryostat. All samples show a strong decrease of the overall external quantum efficiency (EQE) with increasing temperature. Their differences only unveil in the spectral dependence of the EQE. For the GaN samples the EQE at room temperature is dominated by PL from deep defects while the ZnO is still dominated by near-edge emission.