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- Title
Electrical Characteristics of GaN-Based Light-Emitting Diodes on Patterned Sapphire Substrates.
- Authors
Li, Y.; Feng, L.; Xing, Q.; Wang, X.
- Abstract
Patterned sapphire substrate light-emitting diodes display obvious negative capacitance (NC) at large forward biases. This is measured using a method based on a small signal alternating current together with direct I- V plots. The NC in patterned sapphire substrate LEDs grows exponentially with the forward applied voltage. This observation is unexpected and in contrast with Shockley's p- n junction theory, which only includes an increasing diffusion capacitance and not a NC. However, this result is in good agreement with conventional sapphire substrate LEDs. Furthermore, the negative terminal capacitance confirmed the prediction of Laux and Hess' theory. The ideal factor of a patterned sapphire substrate LED is about 5, greatly exceeding the traditional theoretical value. The capacitance increased to a maximum and then gradually decreased, which was similar to the results for a p- n junction. Patterned sapphire substrate LEDs can withstand higher voltages than conventional sapphire substrate LEDs. This work could further confirm the existence of NC.
- Subjects
ELECTRIC properties of gallium nitride; LIGHT emitting diodes; P-N junctions (Semiconductors); SAPPHIRES; SUBSTRATES (Materials science)
- Publication
Journal of Electronic Materials, 2015, Vol 44, Issue 3, p999
- ISSN
0361-5235
- Publication type
Article
- DOI
10.1007/s11664-014-3605-4