Low-Temperature-grown GaAs photoconductors suitable for 1550nm-wavelength illumination

In this communication, we show that ultrafast photoconductors based on low-temperature-grown Gallium Arsenide material exhibit photoresponse values reaching 11 mA/W under 1550 nm CW excitation. This is obtained by using an optical microcavity based on a buried metal layer acting as back reflecting mirror and a top grating electrode in order to improve the external quantum efficiency and by decreasing the post growth annealing temperature of the LT-GaAs layer downto 450 °C. Frequency response measurements are carried out up to 67 GHz by using a 1550-nm-wavelength optical-heterodyne experiment.