Abstract
This article describes advances in thermionic and photoemission materials and applications dating back to the work on thermionic emission by Guthrie in 1873 and the photoelectric effect by Hertz in 1887. Thermionic emission has been employed for electron beam generation from Edison’s work with the light bulb to modern day technologies such as scanning and transmission electron microscopy. The photoelectric effect has been utilized in common devices such as cameras and photocopiers while photovoltaic cells continue to be widely successful and further researched. Limitations in device efficiency and materials have thus far restricted large-scale energy generation sources based on thermionic and photoemission. However, recent advances in the fabrication of nanoscale emitters suggest promising routes for improving both thermionic and photo-enhanced electron emission along with newly developed research concepts, e.g., photonically enhanced thermionic emission. However, the abundance of new emitter materials and reduced dimensions of some nanoscale emitters increases the complexity of electron emission theory and engender new questions related to the dimensionality of the emitter. This work presents derivations of basic two and three-dimensional thermionic and photoemission theory along with comparisons to experimentally acquired data. The resulting theory can be applied to many different material types regardless of composition, bulk and surface structure.
Highlights
HISTORICAL INTRODUCTION Electron emission as a method of energy generation has been studied for nearly two centuries deriving from a foundation of early research in cathode ray tubes, metal-based field emission, and the photoelectric effect
Because a photon-enhanced thermionic emission (PETE) device utilizes semiconductor materials as opposed to metal emitters often used in thermionic emission, here we extend the foregoing analysis of thermionic electronic emission from metals to semiconductors
The theoretical underpinnings of these photoemission processes, culminating in combined effects, presented primarily in a Landauer formulation provide a common basis for analysis and interpretation of experimental results that can derive from a complicated interplay involving broad-band excitation sources, internal scattering mechanisms, and lowdimensional effects associated with nanoscale emitters
Summary
Reviewed by: Davide Mariotti, University of Ulster, UK Zhengjun Zhang, Tsinghua University, China. HISTORICAL INTRODUCTION Electron emission as a method of energy generation has been studied for nearly two centuries deriving from a foundation of early research in cathode ray tubes, metal-based field emission, and the photoelectric effect. Later in the nineteenth century, Elster and Geitel (Angrist, 1976) would investigate sealed devices in which electric current was generated between two electrodes, one hot and one cold, measured utilizing an electrometer. Many of these early studies provided the foundations for cathode and x-ray tubes. While research on thermionic emission continued through the ensuing decades, many of the significant advances in thermionic emission, dedicated toward energy generation, occurred in the www.frontiersin.org
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
