Excitation-Density Dependence of Photoluminescence from Si-Doped AlGaN/AlGaN Multiple Quantum Wells at Low Temperature

Abstract

To investigate the effect of Si doping on Al x Ga 1Àx N/Al y Ga 1Ày N multiple quantum wells (MQWs), photoluminescence (PL) measurements of Al 0:15 Ga 0:85 N/Al 0:20 Ga 0:80 N MQWs with an undoped Al 0:20 Ga 0:80 N barrier layer (undoped MQWs) and with a Si-doped layer (Si-doped MQWs) are compared in weak (1:8 Â 10 À4 to 5:2 Â 10 À3 W/cm 2 ) and strong (360 to 1:28 Â 10 4 W/cm 2 ) optical excitation ranges at 10 K. Based on the results of PL measurement, the carrier injection into the undoped MQWs induced by light illumination in the strong optical excitation range and that into the Si-doped Al 0:15 Ga 0:85 N/ Al 0:20 Ga 0:80 N MQWs in the weak optical excitation range show an increase in the PL intensity and PL peak energy, and a narrowing of the full width at half maximum (FWHM) of the PL peak. Although the internal polarization fields of the undoped and Si-doped MQWs are screened in the strong optical excitation range, the PL intensity of the undoped MQWs is higher than that of the Si-doped MQWs. The difference in the PL intensity is attributed to the formation of a nonradiative center due to Si doping.