Electronics industry is constantly seeking to decrease the energy consumption and increase the performance of the modern electronic equipment. GaAs is one of the most widely used semi-conductors in industries involved in many different types of applications such as integrated circuits, infrared light-emitting diode (LED), laser diode, solar cells, etc. Similarly, GaN semiconductors are gaining increasing importance due to their remarkable properties such as a large band gap and low dielectric constant. Such property makes them potential key materials for high-density data devices or for undersea optical communication systems.
The doping of GaAs semiconductors with Nitrogen atoms is expected to trigger the appropriate properties of the semiconductors towards a specific application. The ternary GaAsxN1-x complexes have therefore been widely studied and appear as potentially interesting system for application in optical and electronics such as infrared diode laser, light detectors, solar cells or optical fibers. In this case study we used ABINIT module within MAPS Platform to study the effect of an increasing amount of Nitrogen on the structural and optical properties of the GaAsxN1-x complex.
GaAs zinc blend structures were built using MAPS crystal builder. This conventional cell was then optimized. Similarly, the different ternary complexes (GaAsxN1-x, x = 0.25, 0.5, 0.75 or 1.0) were studied as well. Finally, the band structure, density of state and optical susceptibility tensors of the different optimized systems were computed using ABINIT. These data directly gave access to the band gap (Eg) of the different compounds. In addition, the complex dielectric function (ε(ω)), dielectric constant (ε0), refractive index (n(ω)) and absorption coefficient (I(ω)) were computed.
This study shows that Nitrogen doping induces a very unusual evolution of some parameters (band gap, dielectric constant) for low N concentration. Since GaAs is one of the most widely used semi-conductor, such ability could lead to important industrial applications. Other optical properties such as the frequency dependent absorption coefficient or refractive index were also computed for all the systems. The maximum absorption coefficient is shifted toward higher photon energy values when the amount of Nitrogen in the system increase. Nitrogen appears, therefore, as a very interesting doping agent for GaAs. Indeed, since some property evolve linearly upon Nitrogen doping and others do not, a wide number of possibilities seems to exist for fine tuning of the properties of GaAs towards a desired set of values,