A family of novel three-terminal devices which relies on the transfer of a quasi-monoenergetic hot electron beam through a thin base is described. The devices are similar in principle to the proposed tunneling amplifier by Mead in the early sixties (“Cold Cathode” or “Metal Base” amplifiers). Results are reviewed and the probable reasons for the poor performances are pointed out. It is predicted that, with a proper choice of parameters, metal-base amplifiers can operate as switches, negative resistance devices and continuous amplifiers in the subpicosecond range. Two subclasses are described: The tunneling emitter (THETA), in the major part of the work, and the nontunneling emitter (BHETA) amplifiers. In the THETA family the metal-oxide-metal-oxide-metal (MOMOM), the MOM-semiconductor (MOMS), and the heterojunctions devices are described. Members of the BHETA family generate quasi-monoenergetic electron beams by injecting electrons by an n + n − or a metal- n − junctions, and include a variety of metals and semiconductor combinations. Very thin films are required in these devices (oxides ∼15 A, metals ∼100 A, semiconductors ∼100 A). The molecular beam epitaxy technique and lattice matching considerations are required for pinhole free semiconductors and metal films with minimum interface states. Sputter-oxidation methods are needed for thin oxide growth. Systems which combine these features with availability of microfabrication make these devices feasible today.

Tunneling hot electron transfer amplifiers (theta): Amplifiers operating up to the infrared

Using the Mehler-Fock transformation to solve Poisson's equation in prolate spheroidal coordinates, we have obtained an exact Green's function solution for all multiple image corrections to the vacuum tunneling barrier for a hyperboloidal tip-planar-anode model of a point-contact junction consisting of identical or dissimilar metals.

A Green's function solution to the image and multiple image interactions for hyperboloidal geometry: Application to metallic pointcontact infrared detectors

Point-contact diodes based either on the mechanism of electronic tunnelling through an insulating barrier or on the thermoelectric effect of hot carriers in heavily doped semiconductors are described. The requirements necessary for these devices to be used as harmonic generators and mixers in the 2–200 THz region are emphasized, and some new developments are reported. Outstanding characteristics of the devices which use either the semimetal antimony or the semiconductors SnTe or Bi2Te3 as a diode base are high detection sensitivity and high mechanical stability over long periods of use either as harmonic generators or as mixers.

Point-contact diodes

Experimental results are reported of high‐frequency (∼ THz) radiation detection by metal‐metal point contacts at low temperatures as a function of bias voltage. The dominant detection mechanism can be attributed to rectification due to electron‐phonon‐scattering‐induced nonlinearity of the I‐V characteristics, a process not observed before.

C. Davis

Papers

Electron Tunneling Spectroscopy of High-Speed W-Ni Submicron Junctions