In a study that was published in Advanced Materials, Prof. Shibing Long and his colleagues from the Chinese Academy of Sciences (CAS) University of Science and Technology of China (USTC) proposed a novel way to create a high-energy photon detector with fast response times and high sensitivity by combining the photoconductive and interface pyroelectric effects using a polycrystal Ga-rich GaOx (PGR-GaOx) Schottky photodiode.
Schematic of the PPD based on PGR-GaOX film and its photoresponse compared to traditional photodiode. Image Credit: Prof. LONG Shibing’s team
Deep ultraviolet (DUV) and X-ray detectors are examples of high-energy photon detectors essential for various sectors, such as industrial science, national security, and medicine. Nevertheless, modern semiconductor materials like Si and α-Se struggle to match the requirements of high-performance detection due to their enormous leakage currents and poor X-ray absorption coefficients.
On the other hand, GaO, a wide bandgap (WBG) semiconductor, has demonstrated excellent promise for high-energy photon detection. However, achieving high-energy photon detectors with high sensitivity and high response speed based on WBG semiconductors has proven difficult due to the inescapable deep energy level traps and the ineffective device structure design of GaO.
To overcome these difficulties, Prof. Shibing Long’s group created the first pyroelectric photoconductive diode (PPD) based on PGR-GaOx. Combining the photoconductive and interface pyroelectric effects significantly enhanced the detection performance.
With responsivities up to 104 A W-1 and 105 μC Gy air-1 cm-2, respectively, the PPD shows exceptional sensitivity to DUV and X-ray, more than 100 times greater than previous detectors constructed from similar materials.
Furthermore, the PGR-GaOx depletion region’s interface pyroelectric effect, caused by polar symmetry, can significantly increase the detector’s response time by 105 times, to 0.1 ms.
Because of the pyroelectric field, the PPD in self-powered mode produces higher gain at the point of light switching than traditional photodiodes. The PPD can also work in bias mode, which is characterized by a strong dependence of the gain on the bias voltage. Increasing the bias voltage will result in an ultra-high gain.
PPD has considerable potential for use in imaging enhancement systems due to its low energy consumption and excellent sensitivity. This study not only reveals that GaOx is a highly promising high-energy photon detector material, but it also proposes novel approaches for developing high-performance, high-energy photon detectors.
Journal Reference:
Hou, X., et. al. (2024) Pyroelectric Photoconductive Diode for Highly Sensitive and Fast DUV Detection. Advanced Materials. doi:10.1002/adma.202314249