Sensitivity of Si-based zero-bias backward diodes for microwave detection

Silicon-based backward diodes incorporating δ-doped active regions for direct detection of microwave radiation with zero external DC bias have been demonstrated at room temperature and characterised for their sensitivity. The resulting backward diodes, which were grown by low temperature molecular beam epitaxy, show a high zero-bias curvature coefficient (γ) of 23.2 V ^-1 with a junction resistance (R_j) of 687kΩ for a 5m diameter mesa diode. The microwave-frequency voltage sensitivity is reported for the first time; a measured sensitivity of 2376 V/W is obtained at zero-bias when driven from a 50 Ω source. An intrinsic 3dB cutoff frequency of 1.8GHz (5m diameter) was determined based on an extracted series resistance of 290 Ω and a junction capacitance of 0.307 pF using a small-signal model established to fit the measured S-parameters.