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A study on the effect of Mg doping in quantum-well (QW) layers on dual-wavelength light-emitting diodes (LEDs) was performed. A series of dual-wavelength LEDs with different Mg doping conditions were fabricated. According to electroluminescence measurement, as the Mg doping concentration and regions varied, improved hole distribution and bottom-QW emission was achieved. This result is in accord with APSYS simulation. In addition, the sample with Mg doping in all QWs showed the highest output power and smallest efficiency droop. It is concluded that Mg doping in QWs could ameliorate the optical and electrical properties of dual-wavelength LEDs. [ABSTRACT FROM AUTHOR]

We report on the effect of a graded AlGaN electron blocking layer (GEBL) on the emission properties of InGaN/GaN multiple quantum wells light-emitting diode (LED). The adoption of GEBL in the LED enhances the electroluminescence intensity and reduces the wavelength blue-shift with increasing injection current. The light output power of the GEBL LED is enhanced by 163% and 415% at 20 and 350 mA, respectively. Moreover, the forward voltage of the GEBL LED is reduced by 0.38 V at the forward current of 20 mA. [ABSTRACT FROM AUTHOR]

Through designing the quantum well (QW) structure by introducing the InGaN interlayers into the GaN barriers, the compressive strain magnitude is significantly decreased. Two distinct emission peaks corresponding to In-rich localized state and quantum well ground state emissions observed from the electroluminescence (EL) spectra demonstrate that the phase separation is enhanced to form In-rich localized states in the original structure with larger strain, but no significant phase separation is observed in the designed structures with less strain. This abnormal phenomenon is contrary to the previous reports that phase separation in the InGaN layer can be suppressed by compressive strain. Therefore, it is suggested that the strain-driven kinetic phase separation should be taken into account in our case to more fully and precisely understand the role played by strain on phase separation that strain can hinder the phase separation thermodynamically but may drive phase separation kinetically. [ABSTRACT FROM AUTHOR]