Influence of Bi and N contents and dot radius on optoelectronic and diamagnetic properties of GaNAsBi strained quantum dot excitons.

The ground state, the fundamental transition, and the binding energies of heavy hole and light hole excitons confined in GaNAsBi/GaAs strained spherical quantum dots (QDs) are calculated. Computing is based on the variational method within the effective mass approximation, combined with the band anti-crossing model. Moreover, the exciton effective Bohr radius a B * is determined using two methods: (i) the radial probability density and (ii) the reciprocal variational parameter, and the limits of these methods are discussed. Theoretical computations of exciton diamagnetic coefficients σ are also presented and compared to the literature. Both excitons optoelectronic and diamagnetic parameters dependence on QD radii R in the range 2–14 nm, and nitrogen and bismuth contents (up to 12%) is obtained with respect to confinement conditions of electric charge carriers, tensile and compressive strain effects, and Coulomb's interaction. We find that the increase of a B * (R) is nearly linear and a B * < R for the pair (x N , y B i ) = (4 , 5) % , but a B * can exceed R for high concentrations of N and Bi. Besides, for a typical sphere radius of 4 nm, GaN x As 1-x-y Bi y /GaAs QDs exhibit broadband emission in the infrared wavelength range of about 1.03–2.55 μm which covers particularly the telecommunication wavelengths of 1.3 and 1.55 μm. By adjusting the adequate dot size and alloy contents, the operating spectral domain can be enlarged, and the emission wavelength can be controlled for several infrared applications. [ABSTRACT FROM AUTHOR]