Application of SCF-LTDP technology for a-Si:H film defective passivation in X-ray PIN-based photosensor

Abstract

The quality and stability of X-ray flat panel detectors and fingerprint identifiers are crucial requirements for high-resolution applications and to ensure successful manufacture and commercially applicability. To achieve higher resolutions, the areas of the photodiodes must be reduced, which results in an increase in the leakage current owing to sidewall defects caused by the photodiodes. This study introduces a supercritical fluid low-temperature defect passivation (SCF-LTDP) treatment to repair the dangling bonds of amorphous silicon (a-Si) PIN-diode-based photo sensors. Unlike traditional atmospheric annealing processes, the hydrogen achieves a low-temperature and high-pressure fluid state in this technique, which offers the advantages of deeper penetration, higher surface tension, and greater viscous force. This technique helps suppress the leakage current generated in the reverse bias voltage by passivating the defects under illumination. The recombination current caused by the defects is, therefore, reduced, resulting in an overall increase of the photocurrent in the X-ray photodiode. The results obtained in this study are beneficial for the development of PIN diodes for panel detector applications.