Amorphous In–Ga–Zn-O thin-film transistor with coplanar homojunction structure

Abstract Amorphous In–Ga–Zn-O ( a -IGZO) thin-film transistors (TFTs) with a coplanar homojunction structure are demonstrated. The coplanar source and drain regions made of a -IGZO were formed by depositing a hydrogenated silicon nitride (SiN X :H) layer onto the a -IGZO layer. The a -IGZO regions on which the SiN X :H layer was directly deposited showed the low resistivity of 4.7 × 10 −3 Ω cm and degenerated conduction. The fabricated TFT showed excellent transfer and output characteristics with a field-effect mobility of 11 cm 2 V − 1 s − 1 , a subthreshold swing of 0.17 V decade − 1 , and an on-to-off current ratio larger than 1 × 10 9 . The width-normalized source-to-drain resistance ( R sd W ) calculated using a channel resistance method was 51 Ω cm. This TFT also showed good stability over environment change and under electrical stress.