Investigation of luminescence centers inside InGaN/GaN multiple quantum well over a wide range of temperature and injection currents
Résumé
InGaN/GaN multiple quantum well-based light-emitting diode LEDs were investigated over a wide range of injection currents (0.04 mA–0.1 A) and temperature (80–370 K)-dependent electroluminescence EL measurements. Two centers were identified for blue luminescence peaking at 2.9 eV and 3.0 eV, denoted as BL2 and BLC, respectively. Although the 3.0 eV center was more effective than 2.9 eV under low temperature (below 160 K), both vanished completely above 170 K due to the activation of non-radiative recombination under a low-current injection regime. At the same time, EL signal intensity was significantly reduced at a high-current injection regime. The recombination through a point trap in GaN barrier layer (known as H1 trap) in InGaN/GaN multi-quantum well structure was non-radiative recombination process: this leads to either vanishing or weakening of 3.0 eV center and its energy depth were determined as 0.9 eV through temperature-dependent dc current–voltage (I–V) and ac capacitance–temperature–frequency (C–T–ω) measurements. The trap depth, thermal quenching of the peak at 3.0 eV, and the sole presence of a peak at 2.9 eV at high temperature might be ascribed to carbon-related defects and agreed with recent theoretical and experimental works in literature.