Characterization of inhomogeneous Ni/GaN Schottky diode with a modified log-normal distribution of barrier heights

Abstract

The current versus voltage (I-V) characteristics of a Ni/GaN Schottky diode are measured from 50 to 400 K and the temperature dependence of the extracted barrier heights and ideality factors is described as a consequence of lateral inhomogeneity at the metal-semiconductor (M-S) interface. It is shown that by invoking a modified log-normal distribution of barrier heights at the M-S interface, the extracted barrier height temperature dependence can be well explained. Further, it is shown that this approach can describe the voltage dependence of the lateral barrier distribution revealing that for effective barrier height values calculated at increasingly higher voltages, the distribution begins to converge on a single value of 0.77 eV. This value is in good agreement with the flat-band barrier height of 0.77±0.02 eV extracted from capacitancevoltage (C-V) measurements on the same device. The same procedure is used to describe the parallel conduction path apparent at low temperatures, revealing its behavior is indicative of an additional Schottky region with an increased density of low barriers which are more heavily perturbed by external bias. Finally, the model is successfully applied to previously published work on various Schottky diodes structures.

Oncurrent-voltage and capacitance-voltage characteristics of metal-semiconductor contacts

“…The SBH and ideality factors have been found to vary with change of the measurement temperature. It is usually assumed that the temperature-dependence n can give the information about the current transport mechanism of a SBD [22,65,[97][98][99][141][142][143][144][145]. As well known, the current transport across the MS Schottky contact is an activation process of the carriers under temperature effect, the current carriers at low temperatures are able to surmount the lower barriers.…”

Plasma and Annealing Treatments to Form Height-Barrier Ni-Based Schottky Contact to n-GaN

“…High-quality Schottky and o contacts are essential components for high-efficiency electronic and optoelectronic devices 1,2 such as laser and light-emitting diodes, 3 Schottky barrier diodes and photodetectors, [4][5][6][7][8] metal-semiconductor-metal photodetector, 9,10 heterostructure field-effect transistors 11 and high-electron-mobility transistors. 12,13 For example, poor Schottky contacts in GaN-based HEMTs resulted in serious leakage current, thereby degrading the gate current characteristics and increasing power consumption.…”