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 GaN/SiC blue light-emitting diodes up to microwave frequencies. A procedure to extract the series resistance (R-s) 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 kHz-10 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 (GaN) semiconductor compounds represent one of the most important breakthroughs in electronics and optoelectronics of recent years. The combination of silicon carbide (SiC) and GaN has recently enabled low-cost blue-emitting diodes to be introduced in industry. (C) 2005 American Institute of Physics