CONDUCTION AND 1/F NOISE ANALYSIS IN AMORPHOUS SILICON THIN-FILM TRANSISTORS

Conduction and low‐frequency noise are analyzed in the channel of hydrogenated amorphous silicon (a‐Si:H) thin‐film transistors. 1/f noise expressions are proposed starting from a simple conduction model describing drain current in the ohmic range. Carrier fluctuations (ΔN model) and mobility fluctuations (Δμ model) are investigated. For long‐channel transistors the conduction is quite similar to crystalline metal–oxide–semiconductor field‐effect transistors but involving low mobility values. The 1/f noise behavior is analyzed by mobility fluctuations as predicted by Hooge’s theory. For small channel transistors a crowding effect appears and access series resistances affect the conduction. The excess noise is then mainly controlled by these resistances when large gate voltages VGS are applied.