Investigation of dilute-nitride alloys of GaAsNx (0.01 < x < 0.04) grown by MBE on GaAs (001) substrates for photovoltaic solar cell devices

Abstract

Dilute-nitride GaAsNx epilayers were grown on GaAs (001) substrates at temperatures of ∼450 °C using a radio-frequency plasma-assisted molecular/chemical beam exitaxy system. The concentration of nitrogen incorporated into the films was varied in the range between 0.01 and 0.04. High-resolution electron microscopy was used to determine the cross-sectional morphology of the epilayers, and Z-contrast imaging showed that the incorporated nitrogen was primarily interstitial. {110}-oriented microcracks, which resulted in strain relaxation, were observed in the sample with the highest N concentration ([N] ∼ 3.7%). Additionally, Z-contrast imaging indicated the formation of a thin, high-N quantum-well-like layer associated with initial ignition of the N-plasma. Significant N contamination of the GaAs barrier layers was observed in all samples, and could severely affect the carrier extraction and transport properties in future targeted devices. Dilute-nitride quantum-well-based photovoltaic solar cells were fabricated having a band-gap energy of 1.19 eV, which was attributed to the dilute-nitride layer.

Design and analysis of GaAsN based solar cell for harvesting visible to near-infrared light

“…The band diagram structure mainly depends on the band gap energy (E g ), electron affinity (χ), and density of doping and defect of the adjacent layers. The value of χ for GaAsN absorber and GaAs layers are assumed to be 4.071 eV and 4.07 eV for Cell 1 and Cell 2, respectively, while for AlGaAs, χ is 3.74 eV [1,7]. The energy difference between the conduction band minima (E c ) and the valence band maxima (E v ) is illustrated as E g for each layer.…”

“…Dilute-nitride based solar cell structures have demonstrated much attention due to their potentiality to increase efficiency by adjusting band gap of alloy-based materials [1]. GaAs/GaAsN structure has been designed for the application of space and large-scale power plant.…”

Design and Simulation of GaAsN Based Solar Cell with AlGaAs Blocking Layer for Harvesting Visible To Near-Infrared Light

“…The band diagram structure mainly depends on the band gap energy (E g ), electron affinity (), and density of doping and defect of the adjacent layers. The value of  for GaAsN absorber and GaAs layers are assumed to be 4.071 eV and 4.07 eV for Cell 1 and Cell 2, respectively, while for AlGaAs,  is 3.74 eV [1,7]. The energy difference between the conduction band minima (E c ) and the valence band maxima (E v ) is illustrated as E g for each layer.…”

“…Dilute-nitride based solar cell structures have demonstrated much attention due to their potentiality to increase efficiency by adjusting band gap of alloy-based materials [1].…”

Origin of two special Raman modes in dilute nitrides

“…[5][6][7] It was found Auger recombination could be suppressed with proper element incorporation [8,9] and lattice constants similar to traditional substrates were exhibited by composition engineering [10]. It is also predicted that dilute nitrides could be used in multijunction solar cells to greatly increase the power efficiency of it [11][12][13][14][15]. Recently, Biccari et al fabricated GaAsN quantum dots with high spatial resolution dehydrogenate GaAsN:H with laser for application in quantum devices [16].…”