SWIR photoresponse of SiGe/TiO2 multilayers with Ge-rich SiGe nanocrystals

• Published in: 2020 International Semiconductor Conference (CAS) pp. 235 - 238
• Main Authors: Lepadatu, A. M., Palade, C., Slav, A., Dascalescu, I., Cojocaru, O., Iftimie, S., Teodorescu, V. S., Stoica, T., Ciurea, M. L.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 07-10-2020
• Subjects: Ge-rich SiGe nanocrystals; Germanium; nanostructured TiO 2; Nonhomogeneous media; Photoconductivity; Silicon; Silicon germanium; Sputtering; Substrates; SWIR photoresponse
• ISSN: 2377-0678
• DOI: 10.1109/CAS50358.2020.9268020

The 1600 nm-extended SWIR photoresponse of SiGe/TiO 2 multilayers with Ge-rich SiGe nanocrystals (NCs) is demonstrated. The SiGe NCs based multilayers are obtained by magnetron sputtering deposition of TiO 2 / 6x(Ge/SiGe/Ge/TiO 2 ) layers on heated p-Si substrate followed by rapid thermal annealing (RTA). Grazing incidence X-ray diffraction and Raman spectroscopy evidence the formation of cubic Ge-rich SiGe NCs and anatase TiO 2 . ITO/Ge-rich SiGe NCs based multilayer /p-Si heterostructure diodes, fabricated by depositing top ITO and bottom Al contacts, show n-p behavior. Photocurrent-voltage characteristics measured at 100 K under integral light illumination of reverse biased diode present a photocurrent higher with up to 2 orders of magnitude than the dark current. Spectral photocurrent increases with bias voltage increase and presents a bandgap-related cutoff wavelength of ~1600 nm due to the high Ge content of SiGe NCs.