AlGaInN resonant-cavity LED devices studied by electromodulated reflectance and carrier lifetime techniques

AlGaInN-based resonant-cavity light-emitting diodes (RCLEDs) emitting in the blue at 480 nm are investigated. The electromodulated reflectivity spectra of these devices exhibit a blue shift of the quantum well (QW) feature when it is perturbed with increasing reverse bias pulses. This is due to a reduction of the quantum-confined Stark-effect and this is used to calculate the average piezo-electric field in the QW as 0.62 ± 0.12 MV/cm. Measurements of the light-current characteristics of processed devices between 20°C and 85°C and of the modulation bandwidth are also used to characterise the samples and to compare their performance with conventional LEDs. Compared to AlGaInP-based RCLEDs, it is found that the AlGaInN-based RCLEDs are less temperature sensitive, while their modulation characteristics are similar, and better than conventional InGaN-based LEDs. The radiative lifetime was estimated to be 2 ns at a current density of 170 A/cm².