GaAsSb-based backward diodes for highly sensitive millimetre-wave detectors

Highly sensitive millimetre-wave detectors based on p-GaAs_0.51Sb_0.49/i-In_0.52Al_0.48As/n-In_xGa_1-xAs backward diodes under zero-bias operation were developed on an InP substrate. Voltage sensitivity of 12300 V/W at 94 GHz was achieved with the GaAsSb-based diode which has a circular mesa with a diameter of 0.9 m. To improve the sensitivity, the indium composition of the n-In_xGa_1-xAs layer and thickness of the i-In_0.52Al_0.48As layer were optimised. Furthermore, a self-aligned process was performed to minimise parasitic resistance at an ohmic contact layer. These GaAsSb-based diodes that are lattice-matched to InP are promising for easy integration with high-performance InP low-noise amplifiers.