Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 31: Poster I: Devices, Quantum Dots and Quantum Wires

HL 31.44: Poster

Tuesday, March 23, 2010, 18:30–20:30, Poster D1

Growth, Characterization and Lasing of CdS Nanostructures — •Julian Kühnel¹, Sebastian Geburt¹, Christian Borschel¹, Michael Kozlik¹, Amanda McDonnell¹, Kristen Sunter², Federico Capasso², and Carsten Ronning¹ — ¹Institute for Solid State Physics, University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany — ²School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA

CdS is a direct II-VI semiconductor with a band gap of 2.42 eV at room temperature, making it a promising material for optoelectronics and photovoltaic applications. Their geometry and optical properties allow the integration as building and functional elements for nanodevices.

CdS nanowires are synthesized by CVD using the VLS mechanism. The morphology and stoichiometry was investigated by SEM and EDX. Dependent on temperature and pressure conditions during growth, an experimental phase diagram was developed. Straight nanowires with diameters around 200 nm and lengths up to several 10 µm have been synthetisized. TEM measurements confirm the high quality of the single crystalline nanowires. CL measurements were performed to study the optical properties of the nanowires and allow a correlation with their morphology. µPL on single nanowire was utilized to investigate the luminescence at high excitation powers. The CdS nanowires show a broad band edge emission with a linear intensity increase up to 2 MW/cm². At higher excitation powers, sharp peaks with defined spacing are evolving. The power dependence clearly shows lasing action in single CdS nanowires above the threshold of 2.5 MW/cm².