It is shown that by using the forward current density-voltage (J-V) characteristics of a Schottky diode, a plot of d(V)/d(ln J) vs J and a plot of the function H(J) vs J, where H(J)≡V−n(kT/q)ln(J/A**T2), will each give a straight line. The ideality factor n, the barrier height φB, and the series resistance R of the Schottky diode can be determined with one single I-V measurement. This procedure has been used successfully to study thermal annealing effects of W/GaAs Schottky contacts.

W/GaAs diodes annealed at temperatures ranging from 100 to 900 °C were investigated with current voltage (I-V) and capacitance voltage (C-V) techniques, Rutherford backscattering spectrometry, scanning electron microscopy, and transmission electron microscopy. Improvements in the diode characteristics were observed after annealing at temperatures below 600 °C. Noticeable degradation in the rectifying behavior of the diodes occurred after annealing at temperatures >600 °C. Correlations between the electrical degradation and the interdiffusion of W and GaAs at the interface were found. Our results strongly suggest that the in-diffusion of W leads to the formation of a diffused, highly resistive region near the W/GaAs interface. The high resistance of this region is believed to be caused by the compensation of the substrate dopants by tungsten acceptors. Annealing the diodes at temperatures >850 °C resulted in reactions between W and GaAs. The W-GaAs reaction leads to islands of W2As3 at the W/GaAs interface, resulting in physical breakdown of the W/GaAs diode.

Influence of interfacial contamination on the structure and barrier height of Cr/GaAs Schottky contacts Appl.

Articles you may be interested inPlasma-induced damage of GaAs during etching of refractory metal contacts Thermal stability and barrier height enhancement for refractory metal nitride contacts on GaAs Appl. Phys. Lett. 50, 445 (1987); 10.1063/1.98169Refractory metal contacts to GaAs: Interface chemistry and Schottky-barrier formationThe electrical characteristics of reactive-sputtered refractory metal nitride contacts on GaAs are investigated for their high-temperature stability after rapid-thermal annealed up to 850·C for 10 s. It is observed that all the contacts studied, including ZrN/GaAs, TiN/GaAs, and NbN/GaAs systems, show improving rectifying characteristics with annealing temperatures up to 800-850 ·C. Not only do they maintain excellent thermal stability and have ideality factors very close to unity, these refractory metal nitride/GaAs contacts actually exhibit a barrier height enhancement ranging from O. 13 eV for NbN/GaAs to 0.30 eV for ZrN/GaAs when contacts are annealed from 500 to 850·C. Concomitantly, the small-signal capacitance of the contacts decreases with higher annealing temperature. The breakdown characteristics of these contacts become avalanche-like and the breakdown voltages increase by twofold. We have invoked the Shannon contact structure (I.e., metallp+ -GaAs/n-GaAs) to account for these hightemperature induced properties. The p -f -GaAs layer formation is attributed to the incorporation of nitrogen into GaAs substrate during sputtering deposition. Comparison between pure refractory metals and their nitride contacts on GaAs are also made with electrical techniques (I-V, c-V) and material characterization techniques (Rutherford backscattering, scanning electron microscopy). Our study suggests that refractory metal nitrides have several advantageous properties for self-aligned GaAs metal-semiconductor field-effect transistor processes.