A normal-incidence PtSi photoemissive detector with black silicon light trapping

A normal-incidence light-trapping scheme relying on black silicon surface nanostructures for Si-based photoemissive detectors, operating in the IR spectral range, is proposed. An absorptance enhancement by a factor of 2-3 is demonstrated for technologically most relevant, ultrathin (2 nm - 3 nm) PtSi rear layers on Si. It is shown that this increase can be translated into an equivalent increase in responsivity because of the absorption limitation of detector performance. Pd2Si/p-Si detectors with black silicon are suggested as promising candidates for room temperature detection in the third optical window with an expected external quantum efficiency in the range of 9%-14%.