Regensburg 2007 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 26: Interfaces/surfaces

HL 26.2: Vortrag

Dienstag, 27. März 2007, 16:15–16:30, H14

Polarity of Space Charge Fields in Second-Harmonic Generation Spectra of Si(100)/SiO₂ Interfaces — Armin Rumpel¹, Bastian Manschwetus¹, Gerhard Lilienkamp¹, Harald Schmidt², and •Winfried Daum¹ — ¹Institut für Physik und Physikalische Technologien, TU Clausthal, Leibnizstr. 4, D-38678 Clausthal-Zellerfeld — ²Institut für Metallurgie, TU Clausthal, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld

Optical second-harmonic generation (SHG) spectra of Si(100)/SiO₂ interfaces exhibit characteristic differences for positively or negatively charged space charge regions (SCRs). These differences originate from interference of second-harmonic light generated in the SCR with that generated by Si atoms in the immediate proximity to the oxide, and characterize the direction of the electric field of the SCR. The spectra are analyzed and modelled by Si interband resonances of the interface and of the SCR. The sensitivity of SHG to the polarity of the space charge is demonstrated for the negative space charge at alkali-modified Si(100)/SiO₂ interfaces, and for the positively charged accumulation layer caused by laser-induced surface traps in thin oxides. The shape of SHG spectra of Si(100)/SiO₂ interfaces in the 3.3-3.8 eV energy range is a signature of the sign of the prevailing interface/oxide charge at silicon interfaces.