Structure-related strain and stress in thin hydrogenated microcrystalline silicon films

• Published in: Journal of physics. Conference series Vol. 253; no. 1; p. 012056
• Main Authors: Christova, K, Alexandrova, S, Abramov, A, Valcheva, E, Ranguelov, B, Longeaud, C, Reynolds, S, Roca i Cabarrocas, P
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.11.2010
• Subjects: Compressive properties; Film thickness; Hydrogenation; Nanocrystals; Photovoltaic cells; Physics; Raman spectra; Silicon films; Strain; Thin films
• ISSN: 1742-6596; 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/253/1/012056

The stress/strain relation for hydrogenated microcrystalline silicon (μc-Si:H) films in the thickness range 10 to 200 nm was studied. It was found from wafer curvature measurements that all deposited films exhibit compressive intrinsic stress, which decreases with film thickness. This finding is in agreement with the stress level seen from the shifts in Raman spectra. The strain was approached through the Raman Mechanical Coefficient for the thin films and was estimated to be −1.4×10−5 (cm−1/MPa). The Raman spectra indicated highly crystalline films. The deconvolution of the spectra into Lorentzian components revealed inclusion of defective nanocrystallites and amorphous phase as well. The fractions of the different constituents were estimated. The contribution of the defective nanocrystallites to the overall stress in the films has been interpreted.