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HL: Fachverband Halbleiterphysik

HL 57: Focussed Session: ZnO-based Semiconductors

HL 57.10: Vortrag

Donnerstag, 25. März 2010, 17:00–17:15, H17

Structural defect bound excitons in ZnO — •Markus R. Wagner¹, Gordon Callsen¹, Jan-Hindrik Schulze¹, Martin Kaiser¹, Ronny Kirste¹, Axel Hoffmann¹, Martin Noltemeyer², Anna V. Rodina³, Stefan Lautenschläger⁴, Sebastian Eisermann⁴, and Bruno K. Meyer⁴ — ¹TU Berlin, Inst. für Festkörperphysik, 10623 Berlin — ²OvGU Magdeburg, Inst. für Exp. Physik, 36106 Magdeburg — ³A.F. Ioffe Physico-Technical Inst., 194021 St.-Petersburg, Russia — ⁴JLU Giessen, I. Physikalisches Inst., 35592 Giessen

Excitons bound to structural defects are a common feature of many semiconductor materials. In ZnO the narrow transition line in luminescence and absorption at 3.333eV is a typical example for this category of excitons. In this contribution we present a comprehensive study of defect bound excitons under the influence of external magnetic and stress fields. The defect centers are identified as neutral donor states with low activation energies despite of their much larger localization energies. Time resolved photoluminescence reveals a significant discrepancy compared to the Rashba-like behavior of the shallow bound excitons. This difference is further supported by the quantitative analysis of the pressure coefficients under the influence of uniaxial stress. The excitation channels of the defect bound excitons are compared with those of the I4 to I9 lines by PLE measurements. Monochromatic CL images provide insights into the microscopic nature of these transitions. Possible defect models for the deeply bound excitons will be discussed.