April published an article in IEDM
In 2019, at the 65th IEEE International Electron Devices Meeting (IEDM 2019) held in San Francisco, USA, Prof. Hang Zhou's research team presented the title "Flexible, active-matrix flat-panel image sensor for low dose X-ray detection enabled by integration of perovskite photodiode and Oxide thin film Transistor ".
X-ray plate image sensors are widely used in medical and industrial examination. Typically, image sensor pixels integrate amorphous silicon thin film transistor (TFT) and amorphous silicon photodiode (PD). Due to the low mobility and high defect concentration of amorphous silicon, the industry has been devoted to developing new X-ray image sensors with high frame rate, low dose and low cost. The team of Associate Professor Zhou Hang has successfully integrated IGZO TFT and Calcium TFT arrays with perovskite photodetectors by taking advantage of the low off-state current of IGZO TFT and the high photoelectric response of perovskite diodes, realizing indirect detection and imaging applications of X-ray, and demonstrated the integrated devices based on flexible substrates. Due to the low dark current of the perovskite diode (~30 nA cm-2), the integrated detector can achieve low dose X-ray detection (2 MGy /s) in indirect detection mode. The indirect X-ray detection sensitivity of perovskite diode reaches 3×103 μC MGY-1 cm-3. The working mechanism of IGZO TFT and perovskite integrated device under grating control and optical control is also described. The results provide a new technical path for developing a new low dose flexible X-ray image sensor.
IEDM is the top conference in the field of microelectronic devices. With a history of more than 60 years, IEDM has been praised as the "Olympic Games in the field of microelectronic devices" by foreign media. It enjoys a high academic status and wide influence in the field of international semiconductor technology. The conference is one of the important platforms for famous universities and research institutions at home and abroad, as well as international well-known enterprises such as Intel, Samsung, IBM, TSMC to report the latest research achievements of semiconductor and electronic devices.
Figure. IGZO TFT/ Perovskite diode array (upper left), IGZO TFT/ perovskite diode imaging pixel structure (upper right),
The transfer characteristic curves of integrated devices under different visible light intensities (lower left) and the imaging effect of optical fiber spots (lower right).