Determining local temperatures in the structures of AlInGaP/GaAs red LEDs in a pulsed operation regime

Abstract

The emission spectra of AlInGaP/GaAs red light-emitting diodes (LEDs) based on a multi-quantum-well heterostructure with distributed Bragg reflectors, operating in a pulsed mode with a pulse repetition rate within 1–10 kHz and a current of 1 × 10⁻³−2 × 10⁻¹ A have been studied in the 20–100°C temperature range. In the regimes with short current pulses and large off/duty ratios, which exclude self-heating of the LED structure, the temperature dependences of the wavelength of emission peaks in the main and side bands exhibit a super-and sublinear behavior, respectively. In the quasi-linear regions of these dependences, the temperature coefficient of wavelength shift for the main peak decreases, while that for the side peak weakly increases with increasing current. The local temperatures (determined from the spectral shift of the main and side emission peaks) and their difference increase with the pulse duration. The difference of thermal resistances, which is calculated from the slope of a plot of the local temperature versus average heating power, is independent of the current and determined by the parameters of layers separating the heterostructure from the reemission region.