The fabrication of germanium-based near infrared photo-resistors on a flexible substrate is reported. The devices were fabricated using plasma enhanced chemical vapor deposition of amorphous germanium on an insulating stack layer of silicon nitride and silicon oxide on a flexible polyimide thin film. The deposited films were annealed using a pulsed laser at different pulse rates and laser energy densities to investigate the effects of germanium recrystallization on the characteristics of the photo-resistors. Electrical and opto-electrical responses of the films have been measured and reported. Surface characterization via scanning electron and atomic force microscopy was used to evaluate the variations in surface roughness of the annealed material versus the amorphous germanium layers. Power spectral density analysis was performed to investigate the effect of laser annealing on the crystalline structure of the germanium samples. Providing a low-temperature processing flow, this work lays the foundation for the development of infrared sensors above flexible substrates with potential applications in wearable electronics among others.
Grayli, S.V., Ferrone, A., Maiolo, L., DE IACOVO, A., Pecora, A., Colace, L., et al. (2017). Infrared photo-resistors based on recrystallized amorphous germanium films on flexible substrates. SENSORS AND ACTUATORS. A, PHYSICAL, 263, 341-348 [10.1016/j.sna.2017.06.005].