SCHOTTKY-CONTACT GATED-4-PROBE ALPHA-SI-H TFT STRUCTURE - A NEW STRUCTURE TO INVESTIGATE THE ELECTRICAL INSTABILITY OF ALPHA-SI-H TFT

In this letter, we describe a new device structure, the Schottky-conta ct (SC) gated-four-probe (GFP) hydrogenated amorphous silicon (a-Si:H) thin-film transistor (TFT) structure, that can be used to study the e lectrical instability of a-Si:H TFT's induced by bias-temperature-stre ss (BTS), In this SC-GFP TFT structure, the evolution of both electron and hole conduction characteristics can be studied before and after B TS without the influence of source-drain contacts, We observed that lo w-bias negative stress induces a reduction in the deep-gap state densi ty, while high-bias negative stress mainly causes trapping of holes in the gate-insulator. On the other hand, positive BTS induces mainly th e trapping of electrons in the gate-insulator, which causes positive s hifts of both electron and hole conduction characteristics.