A High-Performance SiO₂/SiN _x 1-D Photonic Crystal UV Filter Used for Solar-Blind Photodetectors

Abstract

To improve the solar-blind/visible-blind photocurrent response rejection ratio of solar-blind photodetectors, we designed and fabricated a high-performance SiO 2 /SiN x 1-D photonic crystal (PC) ultraviolet (UV) filter on (0 0 0 1) double-polished sapphire substrate. When depositing SiN x , we found that employing NH 3 as nitrogen precursor instead of N 2 can simultaneously improve the peak reflectivity of filter stopband in the designed visible-blind region and the transmissivity in the solar-blind region. Research shows that it is associated with the H atom concentration in SiN x and the generation of Si-O-N transition layer at SiO 2 /SiN x interface. Finally, we obtained a high-performance SiO 2 /SiN x PC UV filter with a stopband reflectivity over 90% from 285 to 345 nm and a transmissivity over 80% in the solar-blind region. The UV filter is also demonstrated to have a good effect in improving the solar-blind/visible-blind photocurrent response rejection ratio of a back-illuminated AlGaN photodetector by depositing it to the back of the detector.

High Performance Wide Angle DBR Design for Optoelectronic Devices

“…The stopband width of actual reflectivity is slightly smaller than simulation, which might be attributed to the H-atom related defects, rough interface and the formation of thin Si-O-N transition layer between SiO2 and SiNx layers. The Si-O-N transition layer with graded composition, has been widely reported in other references, can have major effects on the discrepancy in reflectivity near the edge of stopband [17]. On the other hand, the center wavelength of DBR sample exhibit obvious blue-shift with respect to the increasing light incident angle, as shown in fig.2.…”

“…However, it is very challenging to grow high quality DBR mirror with high reflectivity covering the whole visible light region. Normally, reflectivity in longer and shorter wavelength regions require two contradictory parameters that one needs thicker periodic layers to increase optical path difference and the other needs thinner layers because of the characteristics of DBR mirror [17]. Furthermore, reflectivity of DBR mirror will decrease dramatically with respect to the increasing incident angle due to the increase in optical path difference at higher incident angles.…”

Progress on photovoltaic AlGaN photodiodes for solar-blind ultraviolet photodetection

“…Photonic crystals can be applied for reflective modulation of light by generating photonic bandgaps. When the electromagnetic wave propagates in the optical structure with periodic refractive index variation, the photonic bandgap will be formed to suppress the light propagation in corresponding bands due to the existence of Bragg scattering [38,119,120] . Based on characteristics of photonic crystals, Tan et al designed a type of back-illuminated MSM SBPD integrated with SiO 2 =Si 3 N 4 photonic crystal layers, as shown in Fig.…”