Improving the Transient Response of a Si Metal-Semiconductor-Metal Photodetector with an Additional i-a-SiGe:H Film

An annealed intrinsic hydrogenated amorphous silicon germanium (i-a-SiGe:H) barrier layer deposited on a Si wafer ([111], 4 k Ω-cm) was employed to fabricate a planar interdigitated metal-semiconductor-metal photodetector (MSM-PD). At a bias of 15 V, and an incident light wavelength of 850 nm, this Si-based MSM-PD with an annealed 70 nm i-a-SiGe:H film had a responsivity of about 0.32 A/W, and a dark current density of around 400 fA/µ m2. Also, the temporal response of this device had a rise time of 21 ps, a fall-time of 236 ps and a full-width at half-maximum (FWHM) of 51 ps.