UV & Soft X-ray enhanced Coating
Based on years of coating experience, Spectrophotometer Technology has launched a chip coating service, which is to coat the surface of CCD and CMOS detectors with a layer of fluorescent conversion film (such as Lumogen, GdO₂S). This fluorescent film can convert ultraviolet or soft X-rays into visible light, enabling the detector to efficiently receive ultraviolet signals.
Product overview
- Array detectors—such as front-illuminated CCD and CMOS sensors—typically feature a thick layer of silicon dioxide, silicon nitride, and metals over their sensitive silicon absorption regions. These cover layers cause significant reflection, refraction, and interference effects in the ultraviolet (UV) range, resulting in almost zero UV detection efficiency. Consumer-grade back-illuminated CCD and CMOS sensors usually apply a high-refractive-index (high‑K) coating that strongly absorbs UV light, along with a visible-light anti-reflection film. However, this combination induces pronounced interference effects in the UV, so that despite achieving quantum efficiencies of up to 90% in the visible range, these detectors cannot effectively capture UV spectrum signal. When semiconductor processes are used to enable array detectors to respond to UV or soft X-rays, dedicated chips are typically required—a route that greatly increases overall costs due to expensive mask fabrication.
- To address this issue, Pumo Spectrum, leveraging its extensive coating expertise, has introduced an on-chip coating service. This service involves depositing a fluorescent conversion film (such as Lumogen or GdO₂S) directly onto the surface of CCD and CMOS detectors. The fluorescent film converts UV or soft X-rays into visible light, thereby enabling efficient UV signal detection. With continuous process optimization, Pumo Spectrum’s Lumogen UV enhancement coating now covers a spectral detection range from 180 nm to 1100 nm. In the UV band, it achieves a quantum efficiency of up to 22% and a minimum response wavelength down to 50 nm. Coated consumer-grade CMOS detectors not only meet the demands of atomic spectroscopy applications—including ICP-OES, LIBS, and OES—but are also suitable for semiconductor inspections related to the 193 nm wavelength.