Open AccessИсследование электростатической системы поверхности кристаллов AuNi/GaN диодов Шоттки методом зонда Кельвина атомно-силовой микроскопии
Author(s) -
N. A. Torkhov,
В. А. Новиков
Publication year - 2020
Publication title -
fizika i tehnika poluprovodnikov
Language(s) - English
Resource type - Journals
eISSN - 1726-7315
pISSN - 0015-3222
DOI - 10.21883/ftp.2020.03.49031.9203
Subject(s) - ohmic contact , schottky barrier , work function , schottky diode , thermionic emission , metal–semiconductor junction , schottky effect , materials science , electric field , crystal (programming language) , condensed matter physics , gallium nitride , optoelectronics , diode , chemistry , metal , electron , nanotechnology , physics , layer (electronics) , quantum mechanics , computer science , metallurgy , programming language
Using atomic-force-microscopy investigations of the electrostatic system of the crystal surface of AuNi/ n – n ^+-GaN planar Schottky diodes, it is shown that the electron work function for the surface of metal Schottky contacts depends on their linear size (diameter D ). At D > 120 μm, the work function of the central contact region approaches the work function e φ_Au ≈ 5.40 eV of a continuous metallic gold film. A decrease in the diameter leads to a decrease in the work function to 5.34 eV at D = 120 μm, 5.21 eV at D = 40 μm, 5.18 eV at D = 10 μm, and 5.14 eV at D = 5 μm. The observed decrease in the work function with diameter is related to the increasing influence of the built-in periphery electrostatic field E _ l , which is determined by the area and perimeter of the Schottky contact. The fundamental differences between the thermodynamic and electrostatic systems of TiAlNiAu/ n ^+-GaN ohmic contacts, in contrast to analogous AuNi/ n -GaN Schottky systems, are indicative of the absence of a Schottky barrier in them and the decisive role of the thermionic transport of mobile carriers.