Two types of photodetectors with embedded semiconductor-metal-semiconductor (SMS) structures are proposed. One of them is the embedded metal-semiconductor-metal photodetector (MSM-PD) which has two interdigitating Schottky electrodes in the semiconductor. This has a larger light-sensitive area than the conventional MSM-PD. The other is the back-gated photoconductive detector (BPCD) which has a reduced fall time. The fall time can be reduced by dragging out the slowly moving hole through the back-gate.