Thermal Stability of Schottky Diodes with Pt/n-GaAs Contacts Fabricated by Electrochemical Deposition of Platinum

The paper studies Schottky diodes with Pt/n-GaAs contacts fabricated by electrochemical deposition. The results unveil the dependence of the electrophysical parameters of the diodes with a diameter of contacts from 5 to 500 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{\mu}\mathbf{m}$</tex> on the annealing temperature. The diodes are annealed in nitrogen at 300-550°C for 10 minutes. The barrier height of annealed Pt-GaAs diodes drops from 0.95 to 0.88 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{eV}$</tex> with decreasing diameter; the ideality factor varies from 1.04 to 1.1. Annealing at 300°C enhances the barrier height and ideality factor for smaller diodes (5–50 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{\mu}\mathbf{m})$</tex>: for the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5-\boldsymbol{\mu}\mathbf{m}$</tex> diode, the barrier height increases from 0.89 to 0.94 eV, while the ideality factor decreases from 1.07 to 1.03. At 400°C, the barrier height reverts to the initial value (before annealing), while the ideality factor remains close to 1. The thermal stability of Pt/n-GaAs diodes persists up to 450°C; however, the ideality factor increases. The degradation of electrophysical characteristics begins at 500°C and it can be related to the formation of defects at the interface. The obtained temperature dependencies of electrophysical characteristics are explained by interphase reactions, including the formation of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{PtAs}_{2}$</tex> and PtGa phases that are the key determinants of Schottky barrier properties and thermal stability of the Pt/n-GaAs system.