Growth of autectic thin film structures: H E Cline,J Appl Phys, 53 (8), 1982, 5898–5903

Abstract

The origin of the substrate current of a metal insulator semiconductor field effect transistor (MISFET) when electrons are injected into the gate is investigated. MISFETs with thermal SiO2 (35 Å up to 170 Å) or with a LPCVD SiO2–Si3N4–SiO2 triple stacked layer (with an oxide-equivalent thickness between 115 Å and 130 Å) as gate insulator are used. Comprehensive and accurate quantitative data fitting is presented, considering both the quantum yield and the substrate current. It is shown that thick SiO2 data are consistent with tunneling of hot holes created at the anode by impact ionization. Nevertheless, in thin oxides substrate electron valence-band tunneling plays a dominant role. In the last case a quantitative agreement between data and model is obtained considering a smaller SiO2 electron effective-mass for valence-band electrons. In addition, it is shown that energy quantization of the silicon conduction-band does not change the analysis results. Finally, for the SiO2–Si3N4–SiO2 stacked layer, a model based on Si3N4 electron–valence band injection well explains the experimental data, and suggests an important electron-conduction in Si3N4.