Fig. 3: IdVd Anti-clockwise hysteresis and the Role of Defects.
From: Impact ionization and the paradox of defects in transition metal dichalcogenide FETs
a ID-VD dual sweep (DS) with the end-point of the forward sweep increasing in steps of 5 V shows a significant hysteresis for bias beyond VCr. ID-VG of the device pre and post the bias sweep up to different voltages in the breakdown regime (b) for VDS = 1 V shows a degrading SS and a left VTh shift (c) for VDS = −1 V shows a degrading SS and a right VTh shift. d High field stress reduces the Schottky barrier at the source contact and increases the Schottky barrier at the drain contact. The Schottky barrier height symbolized as the size of the diode in the schematic. e Spatial photocurrent mapping confirms higher electric field on the source edge than at the drain edge from the higher photocurrent with the laser illumination. f Schematic band diagram from point a to b in the inset device schematic, showing the mechanism of the source contact effective barrier lowering due to the high electric field induced local ionization of the deep donor levels, and its impact on the electric field distribution in the channel.
