Direct observation of electron capture & emission processes by the time domain charge pumping measurement of MoS2 FET

TL;DR

This study uses time domain charge pumping to directly observe and differentiate electron capture and emission processes at the interface of MoS2 FETs, providing insights into interface states affecting device performance.

Contribution

It introduces a fast measurement method to directly monitor interface electron dynamics in MoS2 FETs, revealing distinct capture and emission behaviors.

Findings

Detected clear difference between electron capture and emission processes.

Observed current peak during electron capture and broad tail during emission.

Estimated Dit in the range of 10^12 - 10^13 cm^-2 eV^-1, consistent with subthreshold swing data.

Abstract

Understanding interface properties in MoS2 field effect transistors with a high-k gate insulator is critical for improving the performance of the device. Here, by applying the time domain charge pumping method, the elementary process for capture and emission of electrons to the interface states is monitored directly using a fast acquisition system. The main outcome is the detection of the clear difference in the capture and emission process of electrons to the interface states. In addition to the transient current response for gate capacitance, the current peak is observed during electron capture, while the broad tail is detected during electron emission. This different behavior is associated with the fact that the time constant for electron capture is much shorter than that for electron emission. Moreover, Dit is evaluated to be in the range of 1012 - 1013 cm-2 eV-1, which is comparable with that estimated from subthreshold swing.