Photoconductivity and Conductivity Processes in Si-Sn Films Grown on Si(100) Substrate at Room Temperature


Галкин Н. Г., Горошко Д. Л., Китань С. А., Субботин Е. Ю., Тупкало А. В., Чусовитин Е. А.



Goroshko D. et al. Photoconductivity and conductivity processes in Si-Sn films grown on Si (100) substrate at room temperature //Defect and Diffusion Forum. – Trans Tech Publications Ltd, 2018. – Т. 386. – С. 95-101.

Photoresistors based on amorphous Si-Sn thin films (270-285 nm) with different concentration of tin were studied by spectral measurements of photoconductivity at room temperature and by low-temperature measurements of the Hall effect . Electrical contacts to the Si-Sn film was formed by aluminum layer deposition. When the Al contact is illuminated, the spectral sensitivity of the photoresistor with Sn consentration of 19% extends to 2060 nm due to Schottky barrier influence. It was proved that the Si-Sn alloy film provides photoresponse with cut-off energy of 0.98 eV that is close to the indirect band gap in the Si-Sn film. Three deep acceptor levels with activation energies of 90, 114, and 173 meV were found in the Si-Sn thin film (20% Sn) in the temperature range of 50 – 300 K. Sequential activation of the deep levels and their competition leads to a nonmonotonic change of the Si-Sn film conductivity (0.025 - 5.0 (Ω×cm)-1) and mobility of holes (100 – 500 cm2/(V·s)). The transition to the intrinsic conductivity region of the amorphous Si-Sn film was not observed up to room temperature.