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Surface Electronic Properties of Si‐Doped AlGaN and Thermionic Emission Characteristics with Adsorption of Alkali Metal Atoms
Author(s) -
Kimura Shigeya,
Yoshida Hisashi,
Uchida Shota,
Ogino Akihisa
Publication year - 2020
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201900719
Subject(s) - thermionic emission , work function , materials science , doping , mole fraction , analytical chemistry (journal) , x ray photoelectron spectroscopy , common emitter , adsorption , optoelectronics , metal , chemistry , chemical engineering , electron , metallurgy , physics , chromatography , quantum mechanics , engineering
A thermionic energy converter (TEC) is a heat engine with a high theoretical efficiency, but a reduction in operating temperature is required for practical applications. Herein, the experimentally determined thermionic conversion characteristics of Si‐doped GaN films with Cs adsorption at 600 °C are reported. Low‐temperature thermionic emission around 300 °C is also reported for Si‐doped AlGaN surfaces with Cs adsorption. This emission temperature is considerably lower than the operating temperatures of conventional systems with a metal emitter. The AlGaN thin films are grown on n‐type 6H‐SiC substrates, and it is confirmed by ultraviolet photoelectron spectroscopy that the work function decreases as the AlN mole fraction x in the AlGaN samples is increased. Threshold temperatures of thermionic emission decrease with increasing AlN mole fraction and a corresponding reduction in the work function.