EN
The charge build-up and its changes in the amorphous SiO_{2} layer incorporated into a Si MOSFET as a gate oxide due to Fowler-Nordheim tunneling electron injection were investigated. Electron and hole trapping/detrapping by native and generated trap centres were studied by monitoring the charge state of the SiO_{2} traps by means of a drain-source current versus gate-source voltage technique. New interesting effects were observed and their possible mechanisms are presented.