Stress and internal friction associated with light-induced structural changes of a-Si : H deposited on crystalline silicon microcantilevers

Citation
E. Stratakis et al., Stress and internal friction associated with light-induced structural changes of a-Si : H deposited on crystalline silicon microcantilevers, J NON-CRYST, 266, 2000, pp. 506-510
Citations number
13
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
JOURNAL OF NON-CRYSTALLINE SOLIDS
ISSN journal
00223093 → ACNP
Volume
266
Year of publication
2000
Part
A
Pages
506 - 510
Database
ISI
SICI code
0022-3093(200005)266:<506:SAIFAW>2.0.ZU;2-R
Abstract
The study of light-induced changes of the mechanical properties of a-Si:H s hould be valuable in the search for the microscopic mechanisms behind the S taebler-Wronski (SW) effect. We have developed a sensitive technique for st udying such changes by depositing a-Si:H films onto commercial scanning pro be microscope Si microcantilevers. The detection system of the microscope p rovides for measurements of beam bending, oscillation resonant frequency, a nd in-resonance damping factor. The internal friction of an a-Si:H film is much larger than that of crystalline Si and is the largest damping factor o f the bilayer beam. We observed an increase in relative volume, Delta V/V, with photocarrier generation rate, G, and exposure time, t, following Delta V/V proportional to G(0.7)t(0.45) in intrinsic as well as in 1 ppm PH3/SiH 4 doped a-Si:H. The volume changes could be reversed by annealing and were the same for CW and pulsed light exposures using 400 mu s long square pulse s at a rate of 200 s(-1). Based on the magnitude of Delta V/V and the fact that it does not saturate we suggest that the structural changes causing De lta V/V permeate the whole film and are not limited to defect sites. (C) 20 00 Elsevier Science B.V. All rights reserved.