To suppress the dark-current of a planar Si-based metal-semiconductor-metal photodetector (MSM-PD), alternated i-a-Si:H/i-a-SiGe:H grade superlattice-like layers (GSL) were employed as the barrier layer. Under a 0.83 μm incident light power of 10 μW and 5 V bias voltage, the dark-current, knee-voltage and responsivity of device were 0.31 nA, 1.8 V and 0.1 A/W, respectively. Also, the average full-width at half-maximum (FWHM) and fall-time of device temporal response were 116.1 and 388.6 ps, respectively, as measured with a periodic 0.83 μm 60 ps light pulse at a 10 V bias voltage. A very low dark-current and knee-voltage device was obtained owing to the employed alternated i-a-Si:H/i-a-SiGe:H GSL structure.
