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HL: Fachverband Halbleiterphysik

HL 86: Photonic crystals and cavities

HL 86.2: Vortrag

Donnerstag, 3. April 2014, 09:45–10:00, POT 051

The impact of nanoperforation on persistent photoconductivity and optical quenching effects in suspended GaN nanomembranes — •Olesea Volciuc¹, Tudor Braniste², Ion Tiginyanu², Marion Stevens-Kalceff³, Jakob Ebeling¹, Timo Aschenbrenner¹, Detlef Hommel¹, Veaceslav Ursaki⁴, and Jürgen Gutowski¹ — ¹Institute of Solid State Physics, University of Bremen, Bremen 28334, Germany — ²National Center for Materials Study and Testing, Technical University of Moldova, Chisinau 2004, Moldova — ³School of Physics, University of New South Wales, Sydney NSW 2052, Australia — ⁴Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau 2028, Moldova

GaN being ≈ 15-nm thick membranes and nanoperforated in an ordered fashion were fabricated using direct writing of negative charges by focused ion beam and subsequent photoelectrochemical etching of GaN epilayers. The characterization of the photoelectrical properties shows that both continuous and nanoperforated membranes exhibit pronounced persistent photoconductivity (PPC) which can be optically quenched under excitation by 546-nm radiation via impurity levels. We found that optical quenching of PPC occurs also under relatively intense intrinsic excitation of nanoperforated membranes by 355-nm radiation at temperatures T < 100 K. The results are explained by taking into account strong surface localization of charge carriers in nanoperforated membranes and UV-induced reactions occurring at the surface states under intense intrinsic excitation.