Riassunto analitico
Low-frequency noise in MOSFETs is of paramount importance for modern nanoelectronic technologies, both in technology development/optimization and circuit design. This thesis deals with low-frequency noise due to trapping/de-trapping of carriers in the gate dielectric and the theory of carrier number fluctuations. After laying down the theoretical foundation of the study, we derive a new complete set of expressions for the gate and drain power spectral densities of low-frequency noise due to elastic and inelastic trapping/detrapping of channel carriers in MOSFETs, and their correlation. Our calculations highlight a term often neglected in literature, which is very important for ultra-thin dielectrics. Furthermore, the expression for the cross-correlation between drain and gate noise currents due to trapping/de-trapping shows that a single noise generator does not describe correctly the noise process and we identify an interesting relationship between the thermal noise of the gate impedance and the gate noise due to trapping/de-trapping between the free carriers in the channel and the dielectric traps.
The model expressions are validated by comparison with TCAD simulations of scaled MOSFETs with different materials and structures. The results enable trap density extraction from experimental samples with improved accuracy and pave the way to complete and accurate noise compact models for MOSFETs.
|
Abstract
Low-frequency noise in MOSFETs is of paramount importance for modern nanoelectronic technologies, both in technology development/optimization and circuit design. This thesis deals with low-frequency noise due to trapping/de-trapping of carriers in the gate dielectric and the theory of carrier number fluctuations. After laying down the theoretical foundation of the study, we derive a new complete set of expressions for the gate and drain power spectral densities of low-frequency noise due to elastic and inelastic trapping/detrapping of channel carriers in MOSFETs, and their correlation. Our calculations highlight a term often neglected in literature, which is very important for ultra-thin dielectrics. Furthermore, the expression for the cross-correlation between drain and gate noise currents due to trapping/de-trapping shows that a single noise generator does not describe correctly the noise process and we identify an interesting relationship between the thermal noise of the gate impedance and the gate noise due to trapping/de-trapping between the free carriers in the channel and the dielectric traps.
The model expressions are validated by comparison with TCAD simulations of scaled MOSFETs with different materials and structures. The results enable trap density extraction from experimental samples with improved accuracy and pave the way to complete and accurate noise compact models for MOSFETs.
|
