Narrowband Deep UV Sensor on CVD-Grown Diamond Epilayers

In technological applications, encrypted communication and environmental monitoring require specific wavelength detection. As technology advances, the capacity to precisely detect and use distinct wavelengths improves system security, efficiency, and accuracy. The following study introduces a thermally resilient metal-semiconductor-metal deep UV photodetector (MSM DUV PD) fabricated on CVD-grown diamond and demonstrates its properties as a narrowband PD in the DUV range having an advantage over conventional broadband PDs, which require wavelength filters. The fabricated MSM device exhibited a narrow spectral response in the DUV region with an FWHM of 14.4 nm having a peak responsivity at 210 nm wavelength under 5 V bias and maintained the narrowband detection functionality at elevated temperatures up to 423 K. On studying the diamond's cathodoluminescence and photoluminescence properties, it was concluded that radiative and nonradiative recombination via trap energy states in the forbidden band was responsible for narrowband detection. Further, the device exhibits a self-biased operational mode, having a low dark current of 10^-14 A, a detectivity of 2.64 × 10¹¹ Jones, a noise equivalent power of 1.4 × 10^-13 W/Hz^1/2, and a response time of 0.8 s, demonstrating superior operations to detect weak signals from background noise. This study puts forward the potential of CVD-grown diamond as a promising candidate for narrowband DUV photodetection.