Schottky Barriers on GaAs

Abstract

The forward current of Schottky barriers on $n$-type GaAs is investigated as a function of electron concentration in the range of 8×${10}^{17}$ to 8×${10}^{18}$ ${\mathrm{cm}}^{-3\mathrm{}}$ at temperatures 297-4.2°K. Both vacuum-cleaved and chemically polished surfaces are used. The majority of the junctions studied are gold Schottky barriers, but tin and lead contacts are also examined. The predominant current mechanism is field emission at liquid-nitrogen temperature and below for the range of electron concentrations used. These data are in excellent quantitative agreement at 77°K with the field-emission analysis of Padovani and Stratton if one uses a two-band model for the imaginary wave number $k_n$. At 297°K, thermionic field emission predominates, but for an electron density above 3×${10}^{18}$ ${\mathrm{cm}}^{-3\mathrm{}}$ the field-emission mechanism with a two-band model still gives reasonable agreement.