A high-sensitivity, low dark-current planar Si-based metal-semiconductor-metal photodetector (PD) has been successfully fabricated. Under a very weak 0.83-μm incident light power (0.5 μW) and a 4-V bias voltage, the device photocurrent-to-dark-current ratio (Ip/Id) could reach 103. Also, the average full-width at half-maximum and fall time of the device temporal response were 68.18 and 294.7 ps, respectively, as measured with a periodic 0.83-μm 60-ps light pulse at a 10-V bias voltage. In contrast to the previously reported various Si-based PDs, this device exhibited significant improvements in sensitivity and temporal response due to the employed quantum-well-like amorphous silicon-alloy barrier layers.
