| Summary: | In the current COVID-19 scenario, there is an urgent need for developing
efficient and mercury-free deep-ultraviolet (deep-UV) light sources for
disinfection applications. AlGaN-based light-emitting diodes (LEDs) may
be considered as an alternative, but due to their inherent low efficiencies
in the deep-UV spectral region, significant developments are required to
address efficiency issues. Here, a mercury-free chip-size deep-UV light
source is shown which is enabled by high-vacuum chip-scale cavity sealing
overcoming the limitations of both mercury lamps and deep-UV LEDs.
These deep-UV chips are cathodoluminescence based, in which a cavity
is created with high vacuum integrity for efficient field-emission. These
chips demonstrate optical output power ≥20 mW (efficiency ≈4%) and,
owing to the spectral overlap of phosphor cathodoluminescence spectra
and germicidal effectiveness curve, resulted in log 6 (99.9999%) germicidal
efficiency. Additionally, these chips offer high reliability, “instant” ON/OFF
capability, high operational lifetimes, and low-temperature dependence
with complete design freedom.
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