III-N-V low-bandgap nitrides and their device applications

Four families of III-N-V compounds for electronic and optoelectronic applications are presented: InNAsP/InP, GaInNAs/GaAs, Ga(In)NP/GaP and GaInNP/GaAs. InNAsP/GaInAsP quantum wells grown on InP are superior for long-wavelength microdisc lasers (and so expected for edge-emitting lasers), as compared to GaInAs/GaInAsP quantum wells, because of the larger conduction band offset from the addition of a small amount of nitrogen (0.5% to 1%) in the InAsNP quantum wells. GaInNAs/GaAs heterostructures emitting at 1.3 µm at room temperature have stimulated much interest in 1.3 µm vertical-cavity surface-emitting lasers. Here we report the use of GaInNAs as the base of a heterojunction bipolar transistor (HBT), which exhibits a lower turn-on voltage than HBTs with the usual GaInAs base. Incorporating a small amount of N in GaNxP1-x alloys leads to a direct bandgap behaviour of GaNP, and red light-emitting diodes based on a GaNP/GaP double heterostructure grown directly on (100) GaP substrates have been fabricated. Finally, incorporating N into GaInP barriers in a quantum well is shown to lower the conduction band offset, and GaInNP/GaAs could be potentially ideally suited for npn HBTs.