High-frequency modeling of GaN∕SiC blue light-emitting diodes

We report on this work a model to accurately predict the electrical behavior of double-heterostructure $\mathrm{GaN}∕\mathrm{SiC}$ blue light-emitting diodes up to microwave frequencies. A procedure to extract the series resistance $\left(R_s\right)$ from the reflection coefficient is suggested. This procedure offers the advantage of using measurements without any bias current and therefore the obtained values of $R_s$ are influenced neither by the device heating nor by inaccuracies in the calculation of the ideality factor. The junction capacitance and conductance measured in the range $1\mathrm{kHz}–10\mathrm{MHz}$ shows two different relaxation mechanisms, and the total capacitance can be fitted very accurately to a double Lorentzian function. Blue light-emitting diodes and lasers based on gallium nitride $\left(\mathrm{GaN}\right)$ semiconductor compounds represent one of the most important breakthroughs in electronics and optoelectronics of recent years. The combination of silicon carbide $\left(\mathrm{SiC}\right)$ and $\mathrm{GaN}$ has recently enabled low-cost blue-emitting diodes to be introduced in industry.