Guidelines for Ferroelectric-Semiconductor Tunnel Junction Optimization by Band Structure Engineering

Tunneling processes of ferroelectric tunnel junction (FTJ) based on metal-ferroelectric-insulator-semiconductor (MFIS) stack are studied for both n-and p-type semiconductor electrodes using experimentally calibrated model. In the model, the calculation of ON- (J(ON)) and OFF-current (J(OFF)) in MFIS-FTJ considers the electron tunneling from both conduction (CBE) and valence band (VBE), and hole tunneling from the valence band (VBH). Depending on metal work function, doping concentration and remnant polarization, the conduction modes in both n-and p-type MFIS can respectively be classified according to the contribution of minority carriers in semiconductor. The optimal tunneling electroresistance (TER) (approximate to J(ON)/J(OFF)) for the n-type device is achieved, when semiconductor works under depletion/accumulation state driven by polarization reversal. With respect to its p-type counterpart, the accumulation/strong inversion state is preferable. The underlying physics are revealed, that if semiconductor goes into the strong inversion, the tunneling of VBH will increase the J(OFF) and decrease the TER ratio in n-type device, whereas the tunneling of CBE will increase the J(ON) and thus TER ratio in p-type device. Guided by the model, the band structure engineering of MFIS structure is provided to design and optimization of FTJ performance.

Automated summary

This study investigates the tunneling processes of ferroelectric tunnel junction (FTJ) based on metal-ferroelectric-insulator-semiconductor (MFIS) stack for both n-type and p-type semiconductor electrodes using an experimentally calibrated model. The research shows that the conduction modes of n-type and p-type MFIS can be classified depending on the contribution of minority carriers in the semiconductor, and the optimal tunneling electroresistance (TER) for each device is achieved under different operating conditions. The findings provide insights into the band structure engineering of the MFIS structure for designing and optimizing FTJ performance.