Miniaturized Silicon Photodetectors

Silicon (Si) technologies provide an excellent platform for monolithically integrating both photonic [1] and microelectronic [2] functionalities in the same substrate. In the last few years, a variety of passive and active Si photonic and optoelectronic devices have been reported, in particular in the field of photodetection [3][4][5] where new effects and structures have been proposed. Si photodetectors (PDs) at visible wavelengths are a commercial reality, but, unfortunately, they cannot be employed in the infrared (IR) range due the Si transparence over 1100 nm. Historically, the use of germanium (Ge) grown on Si has allowed for the realization of Si-based PDs up to 1550 nm [6]. In recent years, impressive progresses have been achieved by extending the operation of Si PDs to the infrared regime and, recently, thanks to the investigation of new smart structures and effects, the all-Si approach has demonstrated potentialities leading to performances close to those of the well-established germanium (Ge) technology. Moreover, the possibility to integrate new emerging 3D and 2D materials with Si, together with the capability of manufacturing devices at the nanometric scale, has led to the development of new devices with unexpected performance.