Interpretation of barrier height inhomogeneities in Au/In₂S₃/SnO₂/(In-Ga) structures at low temperatures

Abstract

The structure of Au/In₂S₃/SnO₂/(In-Ga) have been examined by current–voltage (I-V) data between 125 and 300 K temperature levels at forward biases. The zero-bias barrier height (Φ _Bo ) and the ideality factor (n) obtained from the linear part of lnI-V characteristics were achieved as cogently dependent to temperature. The Φ _Bo values increase with the increment at temperature where as those of n decrease. The obtained positive temperature coefficient (α = 2.1 × 10³ eV/K) of Φ _Bo was not compatible with the In₂S₃ band gap’s negative temperature coefficient or the ideal diode’s barrier height (BH) behavior. Hence, the plot of Φ _Bo vs. q/2kT have figured to attain an evidence of a Gaussian distribution (GD) of the barrier heights (BHs). The figure for Φ _Bo vs. q/2kT was used to obtain standard deviation (σ _o ) and mean values of BH $\left( {{{\bar{\Phi }}}_{Bo}} \right)$ as 0.88 eV and 0.116 V, respectively. In this way, we modified Richardson [ln(I _o /T ²) − q ²σ_o ²/2k ² T ²] vs. q/kT plot, and the values of ${{\bar{\Phi }}_{Bo}}$ and effective Richardson constant (A*) were extracted as 0.87 eV and 10.25 A/cm² K² from this plot, respectively. It was educed that the I-V data which depends on temperature subjected to the thermionic emission (TE) theory can be set out in full with single GD of the BHs.