一般而言會用金屬作為光偵測器之電極，但會影響受光面積，造成光損耗，所以本研究使用石墨烯作為光偵測器之電極，此優異的薄膜特性及光學穿透率，尤其單層石墨烯在紅外光區高達98.2 %穿透率，近乎透明，藉此提升主動層之照光面積，提升光電流，本實驗使用矽鍺薄膜作為光偵測器主動層，在雷射光波長1310 nm下，響應度可達到0.25 mA/W，其光暗電流比也有明顯區別。 ;In this research, silicon germanium thin films for the application of the near infrared graphene electrode photodetector were fabricated, measured, and analyzed. Germanium is a material for the near infrared wavelength applications, such as optical communication. However, the high cost of germanium wafer make it difficult to be commercialized. To reduce the cost, a silicon germanium thin film has been grown on the silicon substrate as a virtual germanium substrate. Silicon is diffused into the germanium thin film by using thermal annealing method, to form the silicon germanium thin film, whose optical energy gap can be increased, and the absorption wavelength is extended. Another way to improve the property of silicon germanium photodetector is replacing the metallic electrodes as graphene ones. Normally, the metallic electrodes were utilized for the photodetectors. However, a part of light was blocked for the opaque property. In this study, graphene has been used as the electrodes of the photodetector. Because of its excellent characteristic of optical transmittance. The transmittance of a monolayer graphene in the infrared light region is up to 98.2% which can increase the absorption area and the photocurrent. Finally, the responsivity of the silicon germanium photodetector was achieved 0.25 mA/W for the wavelength 1310 nm.
