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HL: Fachverband Halbleiterphysik

HL 48: Quantum dots and wires: preparation and characterization II

HL 48.7: Vortrag

Donnerstag, 29. März 2007, 17:45–18:00, H13

Spin resonance investigations of P-doped Si nanocrystals: Charge compensation and interface states — •Andre R. Stegner¹, Rui N. Pereira¹, Robert Lechner¹, Roland Dietmüller¹, Martin S. Brandt¹, Hartmut Wiggers², and Martin Stutzmann¹ — ¹Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching, Germany — ²Universität Duisburg-Essen, Institute for Combustion and Gas Dynamics, Lotharstrasse 1, 47048 Duisburg, Germany

Silicon nanocrystals (Si-ncs) are attracting interest as a possible base material for low cost electronics and solar cells. To explore the full potential of these materials, a detailed understanding and control of doping is crucial. Si-ncs with diameters in the range 4-50 nm were grown in a low pressure microwave plasma reactor using silane and phosphine as precursor gases. In this type of isolated Si-ncs, the surface termination plays an even more significant role than for Si-ncs embedded in amorphous SiO₂ host matrices. Electron paramagnetic resonance (EPR) spectra of highly doped samples exhibit resonances originating from donor-impurity bands and dangling bond defects at the interface between the Si-ncs and their native oxide shell. Additionally, for the particles with low doping level, the characteristic EPR hyperfine signature of the P donor electrons in Si is also observed, providing proof for substitutional incorporation of dispersed P donor atoms in the Si-ncs. The influence of interface states and charge compensation effects are discussed on the basis of hydrogen thermal desorption spectroscopy and Fourier transform infrared absorption spectroscopy data.