Detection in the contacts at low temperatures: influence of the free electrons concentration on the detecting parameters

Abstract

The diode detectors (DD) play an important role in radio technique and electronics. The use of high frequencies (above 1 GHz) stimulated the careful study of diodes with Schottky barrier. These diodes use the quick-acting metal-semiconductor contacts. The further improvement of their parameters was achieved due to fall of the working temperature (T). This direction was named cryoelectronics, it allows to raise the nonlinearity of the current-voltage dependences and current responsivity. The thermal noise power decreases too. For example there were elaborated DD based on the contacts Pb-pGaAs . At the signal frequency f = 9 GHz and T= 4.2 K these diodes had current responsivity (CR) 500 A/W and noise equivalent power (NEP) 510-15 W/ Hz . At the same frequency and T= 1 K there parameters were: CR ≈ 2500 A/W and NEP ≈ 410-16 W/ Hz . Also the deep cooling allows using the materials with little energy gap width but high mobility of electrons, such as solid solutions Bi-Sb.