High-sensitivity planar Si-based MSM photodetector with very thin amorphous silicon-alloy quantum-welllike barrier layers

A high-sensitivity, low dark-current planar Si-based metal-semiconductor-metal photodetector (PD) has been successfully fabricated. Under a very weak 0.83(mu)m incident light power (0.5 (mu)W) and a 4-V bias voltage, the device photocurrent-to-dark-current ratio (I/sub p//I/sub d/) could reach 10/sup 3/. 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(mu)m 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.