Molecular beam epitaxy of crystalline and amorphous GaN layers with high As content

Journal of Applied Physics

Min

et al. 2014

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A systematic investigation on the effects of growth temperature, Ga flux, and Sb flux on the incorporation of Sb, film structure, and optical properties of the GaN 1Àx Sb x highly mismatched alloys (HMAs) was carried out. We found that the direct bandgap ranging from 3.4 eV to below 1.0 eV for the alloys grown at low temperature. At the growth temperature of 80 C, GaN 1Àx Sb x with x > 6% losses crystallinity and becomes primarily amorphous with small crystallites of 2-5 nm. Despite the range of microstructures found for GaN 1Àx Sb x alloys with different composition, a well-developed absorption edge shifts from 3.4 eV (GaN) to close to 2 eV for samples with a small amount, less than 10% of Sb. Luminescence from dilute GaN 1Àx Sb x alloys grown at high temperature and the bandgap energy for alloys with higher Sb content are consistent with a localized substitutional Sb level E Sb at $1.1 eV above the valence band of GaN. The decrease in the bandgap of GaN 1Àx Sb x HMAs is consistent with the formation of a Sb-derived band due to the anticrossing interaction of the Sb states with the valence band of GaN. V C 2014 AIP Publishing LLC.[http://dx

Section: Introductionmentioning

confidence: 73%

Growth and characterization of highly mismatched GaN1−xSbx alloys

Journal of Applied Physics

Min

et al. 2014

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“…Using highly non-equilibrium LT-MBE with growth temperatures as low as 200°C we have synthesized GaN1-xAsx across the entire composition range [39,76,77]. The resulting alloys are amorphous in the intermediate composition range (0.10 <x< 0.75), with the transition between crystalline to amorphous structure depending on the growth substrate.…”

Section: Lt-mbe Grown Gan1-xasx Over the Entire Composition Rangementioning

confidence: 99%

Highly mismatched GaN_1−xSb_xalloys: synthesis, structure and electronic properties

Sarney

Semicond. Sci. Technol.

et al. 2016

Highly mismatched alloys (HMAs) is a class of semiconductor alloys whose constituents are distinctly different in terms of size, ionicity and/or electronegativity. Electronic properties of the alloys deviate significantly from an interpolation scheme based on small deviations from the virtual crystal approximation. Most of the HMAs were only studied in a dilute composition limit. Recent advances in understanding of the semiconductor synthesis processes allowed growth of thin films of HMAs under non-equilibrium conditions. Thus reducing the growth temperature allowed synthesis of group III-N-V HMAs over almost the entire composition range. This paper focuses on the GaNxSb1-x HMA which has been suggested as a potential material for solar water dissociation devices. Here we review our recent work on the synthesis, structural and optical characterization of GaN1-xSbx HMA. Theoretical modeling studies on its electronic structure based on the band anticrossing (BAC) model are also reviewed. In particular we discuss the effects of growth temperature, Ga flux and Sb flux on the incorporation of Sb, film microstructure and optical properties of the alloys. Results obtained from two separate MBE growths are directly compared. Our work demonstrates that a large range of direct bandgap energies from 3.4 eV to below 1.0 eV can be achieved for this alloy grown at low temperature. We show that the electronic band structure of GaN1-xSbx HMA over the entire composition range is well described by a modified the BAC model which includes the dependence of the host matrix band edges as well as the BAC model coupling parameters on composition. We emphasize that the modified BAC model of the electronic band structure developed for the full composition of GaNxSb1-x is general and is applicable to any HMA.

“…Recently, we succeeded in growing GaN 1-x As x alloys in the whole composition range on sapphire substrate [3,4] using the low temperature molecular beam epitaxy (LT-MBE) method. We found an increase in As content with decreasing growth temperature.…”

mentioning

confidence: 99%

GaNAs alloys over the whole composition range grown on crystalline and amorphous substrates

Broesler

et al. 2011

Phys. Status Solidi C

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Using low temperature molecular beam epitaxy (LT‐MBE) technique we have overcome the miscibility gap of GaAs and GaN alloys and successfully synthesized GaN1‐xAsx alloys in the whole composition range on crystalline (sapphire and silicon) and amorphous (Pyrex glass) substrates. On the N‐rich side we found an increased incorporation of As with decreasing growth temperature. At high enough As content the films lose their crystallinity and become amorphous. On sapphire substrate, the alloys are amorphous in the composition range of 0.17