Deep ultraviolet spectra from BGaN quantum dot structures

Abstract

This work theoretically studies boron-containing ternary and quaternary lattice-matched quantum dot (QD) structures that emit ultraviolet (UV) wavelength by varying the boron mole fraction in the QD active region or the barrier. For BGaN and BAlGaN QD structures, matching to AlN, BAlN, AlGaN barriers and also BInGaN/AlN, the wide-bandgap AlN barrier imposes them to emit at 198–202 nm wavelength. For BInGaN QDs matching to the AlGaN, BAlN, the situation is different. They can emit at the range 252−291nm depending on the barrier and the efficiency of boron content in the barrier in redshifting the wavelength is deduced. The TE and TM gain and spontaneous emission spectra are high and increase under increasing boron in the active region or reducing boron content in the barrier region, exceeding its quantum-well counterpart and of central importance in light-emitting diode applications. Ultra-high gain is obtained from BInGaN/BAlN structure. Gain values are arranged according to the bandgap difference (ΔEg). The range of ΔEg is extended, in the studied structures, to ΔEg=1866−2856 meV, which is of practical importance in UV device applications. The total polarization is decreasing for the Al-containing systems, which is preferred.