Barrier height temperature coefficient in ideal Ti/n-GaAs Schottky contacts

摘要

We have measured the I-V characteristics of Ti/n-GaAs Schottky barrier diodes (SBDs) in the temperature range of 60-320 K by the steps of 20 K. The SBDs have been prepared by magnetron DC sputtering. The ideality factor n of the device has remained almost unchanged between 1.02 and 1.04 from 120 to 320 K, and 1.10 at 100 K. Therefore, it has been said that the experimental I-V data are almost independent of the sample temperature and quite well obey the thermionic emission (TE) model at temperatures above 100 K. fuerthermore, the barrier height (BH) Φ_(b0) slightly increased with a decrease in temperature, 320-120 K. The Φ_(b0) versus temperature plot from intercepts of the forward-bias In I versus V curves has given a BH temperature coefficient of α= -0.090 meV/K. The Norde's function has been easily carried out to determine the temperature-dependent series resistance values because the TE current dominates in the I-V characteristics. Therefore, the Φ_(b0) versus temperature plot from the Norde's function has also given a BH temperature coefficient value of α = -0.089 meV/K. Thus, the negligible temperature dependence or BH temperature coefficient close to zero has been attributed to interface defects responsible for the pinning of the Fermi level because their ionization entropy is only weakly dependent on the temperature.