Effect of threading dislocation density on Ni∕n-GaN Schottky diode I-V characteristics

The impact of threading dislocation density on Ni∕n-GaN Schottky barrier diode characteristics is investigated using forward biased current-voltage-temperature (I-V-T) and internal photoemission (IPE) measurements. Nominally, identical metal-organic chemical vapor deposition grown GaN layers were grown on two types of GaN templates on sapphire substrates to controllably vary threading dislocation density (TDD) from 3×107to7×108cm−2. I-V-T measurements revealed thermionic emission to be the dominant transport mechanism with ideality factors near 1.01 at room temperature for both sample types. The Schottky barrier heights showed a similar invariance with TDD, with measured values of 1.12–1.13eV obtained from fitting the I-V-T results to a thermionic emission-diffusion model. The I-V-T results were verified by IPE measurements made on the same diodes, confirming that the Ni∕n-GaN barrier heights do not show a measurable TDD dependence for the TDD range measured here. In apparent contrast to this result is th...

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