Photosensitive GeSi/TiO 2 multilayers in VIS-NIR

The electrical and photosensing properties correlated with structure and morphology of TiO 2 /(GeSi/TiO 2 ) 2 multilayers are investigated. The multilayers are prepared by magnetron sputtering followed by rapid thermal annealing. Studies of Raman spectroscopy, transmission electron microscopy and X-ray diffraction are carried out. Measurements of dark current versus voltage and temperature are done. The photosensing properties are studied by measuring photocurrent spectra at different temperatures. We obtain multilayers with 10–15 nm Ge 0.6 Si 0.4 nanocrystals (NCs) by annealing at 800 o C. We evidence the tunneling mechanism between neighbor NCs (T −1/2 law) in the dark current-temperature dependence. The photocurrent spectrum has a maximum with position shifting from 940 to 980 nm when the measurement temperature increases from 150 to 300 K, being due to the GeSi NCs.