Diffusion current and its effect on noise in submicron MOSFETs

Reports a significant shot noise component in submicron metal-oxide-semiconductor field effect transistors (MOSFETs) operating in strong inversion. A quasi-three-dimensional (3D) MOSFET simulation was used to compare simulated noise parameters to measured data and to verify the model. For long channel devices, thermal noise was confirmed to be the main source of noise in accord with the conventional theory. In contrast, for submicron devices the shot noise appeared to be dominant. The shot noise component is primarily produced near the source of the device and is believed to be caused by the diffusion current.