Study of structural and optical properties of InSb-doped SiO2 thin films

• Published in: Journal of non-crystalline solids 2005-07, Vol.351 (21-23), p.1819-1824
• Main Authors: CAPOEN, B, LAM, V. Q, TURRELL, S, VILCOT, J. P, BECLIN, F, JESTIN, Y, BOUAZAOUI, M
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2005.04.023

The non--linear absorption and the structure of rf--cosputtered SiO2:InSb films were investigated after different heat--treatments at temperatures ranging from 200 to 900 deg C. The heat--treatment was 1min or 4h in an atmosphere of nitrogen or under vacuum, respectively. After annealing at a temperature higher than 200 deg C, the presence of nanocrystallites in the layers was detected by transmission electron microscopy (TEM) and Raman spectroscopy. The growth of either Sb or InSb nanocrystals essentially depends on both the annealing temperature and the heat--treatment time. Particularly, it was shown that a rapid thermal annealing (RTA) is necessary to obtain crystals of InSb with size estimated to be about 15nm. The largest positive non--linear coefficient beta, as measured by the Z--scan method at 1064nm in a nanosecond regime, was found to be equal to 1*8x10(--3)cm/W when the films contain InSb particles of larger size (up to 100nm). However, when increasing the incident irradiance on the sample, the non--linear effect does not increase and seems to saturate, which can explain the discrepancies observed with previous works on similar materials. This disagreement may also be due to different response times of the non--linearities related to thermal effects in the continuous wave (CW) open--aperture Z--scan configuration.