| Summary: | To improve the performance of III-nitride compound semiconductor-based optoelectronic devices, highly reflective distributed Bragg reflectors (DBRs) are a requirement. In this report, AlN and Al<sub>1−x</sub>In<sub>x</sub>N layers were first sputtered and characterized concerning their optical, structural and morphological properties. Ellipsometry measurements were used to determine the optical constants (refractive index, <i>n</i> and coefficient of extinction, k, in dependence of the wavelengths of the layers. The indium content of the Al<sub>1−x</sub>In<sub>x</sub>N film was investigated by X-ray photoelectron spectroscopy analysis. Subsequently, AlN/Al<sub>1−x</sub>In<sub>x</sub>N DBRs with high reflectivity spectra operating in the UV A, B and C were designed and fabricated on Si (111) and SiO<sub>2</sub> substrates by radio frequency (RF) magnetron sputtering. The DBRs consist of an eight-pair AlN/Al<sub>0.84</sub>In<sub>0.16</sub>N at 235 nm, 290 nm and 365 nm with reflectances of 86.5%, 97.7% and 97.5% with FWHM of 45 nm, 70 nm and 96 nm, respectively. Atomic force microscopy analysis yielded a Root Mean Square (RMS) of 2.95 nm, implying that the DBR samples can achieve reasonable smoothness over a wide area. Furthermore, the impact of an annealing phase, which is frequently required during device growth, was investigated. Our findings indicate that AlN and Al<sub>1−x</sub>In<sub>x</sub>N are suitable materials for the fabrication of deep UV DBRs.
|
|---|