  Using nanowires for photodetection constitutes an opportunity to enhance the
absorption efficiency while reducing the electrical cross-section of the
device. They 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. Within a
nanowire, it is possible to implement axial and radial (core-shell)
heterostructures. These two types can be combined to obtain three-dimensional
carrier confinement (dot-in-a-wire). The incorporation of heterostructures in
nanowire photodetectors opens interesting opportunities of application and
performance improvement. Heterojunctions or type-II heterostructures favor the
separation of the photogenerated electrons and holes, and the implementation of
quantum dots in a nanowire can be applied to the development of quantum
photodetectors. This paper provides a general review of latest progresses in
nanowire photodetectors, including single nanowires and heterostructured
nanowires.
