Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 50: Nanodr
ähte

HL 50.7: Vortrag

Dienstag, 8. März 2005, 12:15–12:30, TU P-N201

Paramagnetic Defects of Chemically Modified Silicon Nanowires — •A. Baumer¹, M. Loeb¹, M. Stutzmann¹, M.S. Brandt¹, F.C.K. Au², and S.T. Lee² — ¹Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching, Germany — ²Center of Super-Diamond and Advanced Films & Department of Physics & Material Science, City University of Hong Kong, Hong Kong SAR, China

The paramagnetic defects of Si nanowires (SiNWs) obtained by oxide-assisted growth were studied by electron spin resonance spectroscopy. For the as-grown nanowires with a typical diameter of 10−15 nm, three different defects were found: Dangling bonds or P_b-centers with g=2.0065 , located at the interface of the crystalline core to the surrounding oxide, E′-centers with g=2.0005 and EX-centers with g=2.00252 , located in the oxide. For the EX-centers, the characteristic hyperfine lines separated by 16.4 G were detected. The as-grown Si nanowires showed a spin density of about 10¹¹ cm⁻². H termination of the nanowires via hydrofluoric acid decreases the spin density drastically to 2· 10⁹ cm⁻². Further chemical modification of the H-terminated nanowires via hydrosilylation with alkenes provides alkyl-terminated nanowires as verified by Fourier-transform infrared-spectroscopy. The alkyl-terminated nanowires showed a spin density of about 10¹⁰ cm⁻², which is stable for at least several weeks.