Ultraviolet detecting properties of amorphous MgInO thin film phototransistors

The ultraviolet (UV) detecting properties of Mg doped In 2 O 3 (MgInO or MIO) bottom gate thin film transistors (TFTs) were investigated. The optical measurements show that the introduction of Mg dopants effectively widens the optical band gap of In 2 O 3 . The cutoff wavelength of MIO films is pushed to deep UV as Mg content increases. Fabricated MIO TFTs with high Mg content demonstrate appraisable UV detecting properties with a dark current of 10 −14 A, a UV to visible rejection ratio of 10 3 , a responsivity of 3.2 A/W (300 nm) and a cutoff wavelength of 320 nm, which can be put to good use in deep UV detection. The dynamic photo-response measurement shows that the persistent photo-conductivity (PPC) effect can be alleviated by imposing a transient positive gate pulse.