The optical properties of BAlN, BGaN and AlGaN ternary alloys are investigated using hybrid density functional for the design of lattice-matched optical structures in the ultraviolet spectrum. The calculated AlGaN properties agree well with previous reports, validating the model. A peculiar non-monotonic behavior of the refractive index as a function of the boron composition is found. The results of this calculation are interpolated to generate a three-dimensional dataset, which can be employed for designing a countless number of lattice-matched and –mismatched heterostructures. These heterostructures could span a range of operating wavelength well into the deep ultraviolet with refractive indices ranging from 1.98 to 2.41 for AlN at 0 eV and GaN near the GaN bandgap, respectively. An example is shown where a lattice-matched heterostructure, AlN/B0.108Ga0.892N, is applied for DBR applications with a large index difference. A DBR comprising the AlN/B0.108Ga0.892N heterostructure at the UV wavelength of 375 nm is found to exceed 93% peak reflectivity with only 10 pairs and reaches 100% reflectivity with 35 pairs. For a chosen design with 25 pairs, the DBR has a peak reflectivity of 99.8% and a bandwidth of 26 nm fulfilling the requirements of most devices especially ultraviolet vertical-cavity surface emitting lasers.
Bibliographical noteKAUST Repository Item: Exported on 2021-11-24
Acknowledged KAUST grant number(s): BAS/1/1664-01-01, REP/1/3189-01-01, URF/1/3437-01-01, URF/1/3771-01-01
Acknowledgements: The authors acknowledge support of KAUST Baseline Fund BAS/1/1664-01-01, Competitive Research Grants URF/1/3437-01-01 and
URF/1/3771-01-01, and GCC Research Council REP/1/3189-01-01.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Metals and Alloys
- Polymers and Plastics
- Surfaces, Coatings and Films