A theoretical investigation of the band alignment of type-I direct band gap dilute nitride phosphide alloy of GaN sub(x)As sub(y)P sub(1-x-y)/GaP quantum wells on GaP substrates

The GaP-based dilute nitride direct band gap material Ga(NAsP) is gaining importance due to the monolithic integration of laser diodes on Si microprocessors. The major advantage of this newly proposed laser material system is the small lattice mismatch between GaP and Si. However, the large threshold current density of these promising laser diodes on Si substrates shows that the carrier leakage plays an important role in Ga(NAsP)/GaP QW lasers. Therefore, it is necessary to investigate the band alignment in this laser material system. In this paper, we present a theoretical investigation to optimize the band alignment of type-I direct band gap GaN sub(x)As sub(y)P sub(1-x-y)/GaP QWs on GaP substrates. We examine the effect of nitrogen (N) concentration on the band offset ratios and band offset energies. We also provide a comparison of the band alignment of type-I direct band gap GaN sub(x)As sub(y)P sub(1-x-y)/GaP QWs with that of the GaN sub(x)As sub(y),P sub(1-x-y)/Al sub(z)Ga sub(1-z) P QWs on GaP substrates. Our theoretical calculations indicate that the incorporations of N into the well and Al into the barrier improve the band alignment compared to that of the GaAsP/GaP QW laser heterostructures.