Nanowire photodetectors based on wurtzite semiconductor heterostructures

Using nanowires for photodetection constitutes an opportunity to enhance the absorption efficiency while reducing the electrical cross-section of the device. Nanowires present interesting features like compatibility with silicon substrates, which offers the possibility of integrating detector and readout circuitry and facilitates their transfer to flexible substrates. The incorporation of heterostructures in nanowire photodetectors opens interesting prospects for application and performance improvement. Within a nanowire, it is possible to implement axial and radial (core-shell) heterostructures, and these two types can be combined to obtain the three-dimensional carrier confinement (dot-in-a-wire) which is required for the development of quantum photodetectors. If the nanowires present wurtzite crystallographic structure, the presence of heterointerfaces can induce internal electric fields due to the difference of polarization between the constituents. Such polarization-induced internal electric fields, like those induced by heterojunctions or type-II heterostructures, can be ingeneered to favor the separation of the photogenerated electrons and holes. This paper provides a general review of latest progresses in nanowire photodetectors, including single nanowires and heterostructured nanowires.