| Sb-heterostructure backward diodes have been designed, fabricated, characterized and modeled for zero-bias millimeter-wave detection and imaging. Detectors with three different heterostructures and various active areas have been characterized. The effect of the incorporation of a p-type delta-doping layer in the cathode, as well as the vertical and lateral scaling of the device structure on the detector's performance has been studied. A typical 10-A barrier thickness detector with delta-doping layer and an active area of 0.85x0.85 mum2 has been demonstrated with a record-high sensitivity of 4200 V/W, a cut-off frequency of 620 GHz, and an NEP of 0.24 pW/Hz1/2 at 94 GHz for a conjugately-matched RF source. In addition to the directly-measured performance at W-band, predictions of the device performance through Y band and beyond using a non-linear device model show the potential of the Sb-heterostructure detectors for high-frequency operation in millimeter- and submillimeter- wave imaging systems. The temperature-dependent dc and microwave characterization of these devices demonstrate very favorable characteristics have been achieved for the Sb-heterostructure detectors for both ambient and cryogenically-cooled applications. A simple physical model that captures the temperature-dependent effects is described. The high sensitivity, low noise, wide bandwidth, good detection linearity and favorable temperature-dependence make the Sb-based device a promising candidate for improving the performance of passive millimeter and submillimeter imaging systems. |
