II-VI quantum-well structure produces red-green-blue lasing at room temperature

II-VI quantum-well structure produces red-green-blue lasing at room temperature

Scientists at the City University of New York (New York) produced room-temperature optically pumped laser emission across the entire visible spectrum from three zinc cadmium magnesium selenide/zinc cadmium selenide (ZnCdMgSe/ZnCdSe) quantum-well laser structures grown on indium phosphide (InP) substrates. The resulting quaternary materials system has potential uses in integrated red-green-blue full-color displays.

To design the totally lattice-matched or pseudomorphic laser structures, L. Zeng and colleagues use cladding and waveguiding ZnCdMgSe layers and an active ZnCdSe layer. The structures also allow growing a symmetrically strained zinc selenide/zinc telluride (ZnSe/ZnTe) superlattice or lattice-matched ZnSeTe alloys that are easily doped for the ohmic contact without introducing lattice-mismatch defects. Layers are grown lattice-matched to In¥substrates with bandgaps from 2.18 to 3.5 eV. Varying quantum-well thickness and composition tunes the emission--otherwise the structures are almost identical. The researchers know of no other set of semiconductor materials in which the structures are pseudomorphic on one substrate and produce light emitters operating throughout the visible spectrum. Conventional materials used in light-emitting-diode-based full-color displays do not combine easily on one substrate.