Electron spin resonance in laser-crystallized polycrystalline silicon-germanium thin films

• Published in: Physica status solidi. A, Applications and materials science Vol. 207; no. 3; pp. 570 - 573
• Main Authors: Weizman, M., Scheller, L.-P., Nickel, N. H., Lips, K., Yan, B.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Berlin WILEY-VCH Verlag 01.03.2010; WILEY‐VCH Verlag; Wiley-VCH
• Subjects: 61.72.Hh; 61.72.Mm; 68.55.−a; 76.30.−v; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron paramagnetic resonance and relaxation; Exact sciences and technology; Magnetic resonances and relaxations in condensed matter, mössbauer effect; Physics; Defect states; Grain boundaries; Dangling bonds; Defect density; Electrical conductivity; Localized states; Ge-Si alloys; Crystallization; Laser assisted processing; Polycrystals; Electron paramagnetic resonance
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.200982897

The defect properties of laser‐crystallized polycrystalline silicon–germanium (Si–Ge) thin films on glass substrates were investigated with electron spin resonance (ESR) and conductivity measurements. The ESR measurements reveal that laser‐crystallized poly Si1−xGex thin films with 0 < x < 0.84 contain a dangling‐bond concentration of about Ns = 4 × 1018 cm−3, roughly independent of the Ge content in this range. Surprisingly, the ESR signal vanishes completely for the Ge‐rich alloys (x > 0.84) and instead a broad atypical signal appears that we attribute to electric dipole induced spin resonance (EDSR). Samples that showed this behavior exhibited a nearly temperature‐independent electrical conductivity for temperatures between 20 and 100 K. The data are discussed in terms of a model that is based on the formation of a defect band along the grain boundaries in the vicinity of the Fermi level.