Abstract
This paper presents a silicon ultraviolet radiation sensor with over 90% UV internal quantum efficiency (QE) and high selectivity to the UV waveband without using optical filters. The sensor was developed for applications that require UV measurement under strong background visible and near-infrared (NIR) lights, such as solar UV measurement, UV-C monitoring in greenhouses or automated factories, and so on. The developed sensor is composed of monolithically formed silicon photodiodes with different spectral sensitivities: a highly UV responsive photodiode with internal quantum efficiency (QE) of nearly 100% for UV light, and a lowly UV responsive photodiode with UV internal QE lower than 10%. The photodiodes were optimized to match their visible and NIR light responsivity, and the UV signal is extracted from the background radiation by using the differential spectral response method. With this approach, an internal QE of over 90% for UV light was obtained, with a residual internal QE to non-UV light lower than 20% for 400 nm, 5% for 500 nm, 2% for 600 nm and 0.6% to NIR light. The developed sensor showed no responsivity degradation after exposure towards strong UV light. It was confirmed by the simulation results that the residual responsivity is further suppressed by employing an on-chip band-rejection optical layer consisting of several layers of silicon oxide and silicon nitride films.
Highlights
Ultraviolet (UV) radiation sensing has been extensively researched and applied to several fields including scientific analysis, industrial, medical, safety systems and so on [1,2,3,4]
For applications that require UV-C (190 nm to 280 nm) or UV-B (280 nm to 315 nm) light sensing, such as solar UV-B measurement and flame detection, we propose using the developed differential spectral response sensor with an interference interlayer composed of several stacks of SiO2 and SiN
The spectral response was measured by a system consisting of the EQ-99 light source, from
Summary
Ultraviolet (UV) radiation sensing has been extensively researched and applied to several fields including scientific analysis, industrial, medical, safety systems and so on [1,2,3,4]. Some examples of already reported applications are UV spectroscopy [5], UV cure process monitoring [6], solar UV measurement for healthcare applications [7], flame detection [8], semiconductor process control [9], among many others. 200 nm) and extreme UV (1 nm to 10 nm) wavebands are useful for monitoring of photolithography processes [10]. Due to this broad scope of applications, there is an increasing demand for compact. High selectivity of responsivity to UV light is crucially important in the applications that require UV radiation detection under ambient visible and near-infrared (NIR) light, such as solar UV measurement and flame detection. A sensor with a simple and low-cost manufacturing process is desirable for cost-sensitive applications
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