Semimetal-semiconductor rectifiers for sensitive room-temperature microwave detectors

In contrast to traditional metal-semiconductor (i.e., Schottky) junctions, ErAs : InAlGaAs heterojunctions have recently been shown to provide highly "engineerable" electrical rectification characteristics through the tuning of the Schottky barrier height and differential resistance, while maintaining the very low specific capacitance for which Schottky diodes are famous. We demonstrate that these new rectifiers can operate effectively at zero bias and can be extremely sensitive at microwave frequencies. We report a tangential sensitivity of − 63 dBm at 3.1 GHz in an 8.0 KHz bandwidth, corresponding to a noise-equivalent power (NEP) of 8.9 × 10 − 13 W ∕ Hz 1 ∕ 2 . We attribute this noise performance to the high rf-to-dc current responsivity ( ∼ 8 A ∕ W ) , zero bias operation, and noise source reduction. The new diodes are found to be ∼ 19 dB more sensitive than the best available Hewlett-Packard zero-bias diodes at comparable frequencies.