Realize Diamond DUV Detector

Diamond, as a material with ultra wide bandgap, high thermal conductivity, chemical inertness, high insulation, and radiation resistance, is considered an ideal candidate material for manufacturing DUV photodetectors. The development of diamond based photodetectors has made some progress, but the sensitivity and overall performance still need to be further improved to meet the needs of practical applications. Researchers are exploring the synergistic effect of surface states and deep defects to achieve ultra-high gain DUV photodetectors that operate at low voltages, in order to address the challenges of single-chip integration and promote the development of DUV detector technology compatible with integrated circuits.

 

In the field of ultra wide bandgap semiconductors, researchers are working to develop deep ultraviolet (DUV) photodetectors with ultra-high gain, aiming to achieve performance comparable to photomultiplier tubes (PMT). These detectors are crucial for blind detection and communication in the wavelength range of 200-280 nanometers, as they can provide high sensitivity, high speed, high spectral selectivity, high signal-to-noise ratio, and high stability. However, existing detectors based on ultra wide bandgap semiconductors, such as AlGaN and Ga2O3, face challenges such as high operating voltage, high lattice defect density, phase segregation, and sensitivity to magnetic fields, which limit their further development in performance.

 

The team led by Liao Meiyong from the National Institute of Materials Science and Technology in Japan has demonstrated that the synergistic effect of surface states and deep defects on Ib type single crystal diamond (SCD) substrates can achieve ultra-high gain DUV photodetectors (PD) with low operating voltages (<5V). The overall photoresponse of diamond DUV-PD, such as sensitivity, dark current, spectral selectivity, and response speed, can be easily customized by hydrogen or oxygen termination on the SCD substrate surface. Under 220 nm light, the DUV response rate and external quantum efficiency exceed 2.5 × 104 A/W and 1.4 × 107%, respectively, which is comparable to PMT. The DUV/visible light suppression ratio (R220 nm/R400 nm) is as high as 6.7 × 105. The depletion of two-dimensional hole gas by deep nitrogen defects provides low dark current, and the filling of ionized nitrogen under DUV irradiation generates a huge photocurrent. The synergistic effect of surface states and intrinsic depth defects has opened up the way for the development of DUV detectors compatible with integrated circuits.

 

The related achievements were published in Advanced Functional Materials under the title "Synergistic Effect of Surface States and Deep Defects for Ultra high Gain Deep Ultra Violet Photodetector with Low Voltage Operation".