Wide bandgap semiconductors for radiation detection in extreme conditions

Detecting high-energy ionizing radiation is crucial in many fields. At nuclear power plants, detectors are a critical piece of safety equipment, while in science and medicine, they are an important diagnostic tool. While most commercial systems use indirect detectors like scintillators and gas sensors, semiconductor direct-conversion detectors are gaining attention due to their increased detection efficiency and spatial resolution. However, common silicon-based detectors often struggle in highly irradiated environments or high-temperature conditions.

Bai et al. developed an alternative semiconductor direct-conversion detector based on a PtO_x/β-Ga₂O₃ Schottky barrier diode.

Wide bandgap semiconductors, like Ga₂O₃, have much greater stability in extreme environments compared to their silicon-based counterparts. However, Schottky diodes made from these materials often face reverse current leakage, leading to increased background noise and poor performance. One potential way to mitigate this leakage is to increase the barrier height of the diode contacts.

“Semiconductor crystals are prone to defects, and the accumulation of fixed negative charges inside certain defects leads to an increase in the electric field, which increases leakage,” said author Xiaohu Hou. “Our detector is based on a Schottky diode structure, and the reverse leakage current is suppressed by introducing the high potential barrier of Ga₂O₃-PtO_x.”

In tests, the team’s detector exhibited high stability and reduced current leakage. They plan to continue to develop their detector and explore its performance under extreme conditions.

“We will try to improve the voltage tolerance of the device by reducing the doping concentration of the epitaxial layer and designing the terminal structure of the device, thereby improving the charge collection efficiency of the detector,” said Hou.

Source: “Alpha particle detection based on low leakage and high-barrier vertical PtO_x/β-Ga₂O₃ Schottky barrier diode,” by Shiyu Bai, Xiaohu Hou, Xiangdong Meng, Lei Ren, Chen Li, Zhao Han, Shunjie Yu, Yan Liu, Zhixin Peng, Yuncheng Han, Xiaolong Zhao, Xuanze Zhou, Guangwei Xu, and Shibing Long, Applied Physics Letters (2024). The article can be accessed at https://doi.org/10.1063/5.0216689 .