Wolfgang M. Feist

Research in tunnel emission

The tunnel cathode is a promising development in the search for a cold emitter. Ideally, it should operate at high current densities, low cathode power, low noise, and at low temperatures. High-frequency modulation of emission is also possible A research effort has been under way in various countries in recent years, with regard to the development of electron emission from cold, solid-state devices into vacuum, an insulator, or a semiconductor. The term “cold” in this connection is used to describe devices that emit electrons at operating temperatures of approximately 300°K and below. This is in contrast to the emission of electrons from a heated material in which the electrons receive the excess energy necessary for their emission exclusively from their equilibrium with the thermal vibrations of the heated host body.

Thermodynamical Limits on the Bandwidth and Conversion Efficiency of Incoherent Recombination Radiation from a Semiconductor Diode

The second law of thermodynamics imposes a limit on the maximum efficiency achievable with any rectifier in converting radiation into dc power. By using the second law and Bose photon statistics, a general expression is derived showing that this efficiency depends upon the bandwidth and effective temperature of the incoming radiation. Only for completely coherent radiation can the conversion efficiency be unity. The theoretical implications are illustrated by examining specific thermodynamic cycles involving idealized recombination diodes and thermodynamically ideal rectifiers. The relationship between minimum bandwidth of radiation and bias voltage in a recombination diode is derived. The connection between conversion efficiency and Carnot efficiency is made clear.