Abstract
The operation of a new class of devices employing the principle of tunnel emission is discussed. It is shown that a controlled electron source may be obtained with the use of a metal‐insulator‐metal diode structure where the second metal layer is very thin. A triode geometry may be secured by the addition of an additional insulator and a metal collector layer. Limitations on the operating frequency, current density, and current transfer ratio of such devices are discussed. Experimental results on diode and triode are discussed. Experimental results on diode and triode structures which employ several materials are presented. Successful triodes and vacuum emitters have been realized with the use of Al2O3 insulating films. Experiments using Ta2O5 are described, and the results are discussed.