Fig. 4: Time and temperature stability of chloroform-doped WSe2 devices.
From: Low resistance p-type contacts to monolayer WSe2 through chlorinated solvent doping
a ID vs. VGS curves of a Lch = 1 μm device immediately after doping and after 6, 60, 134, and 243 days. b Threshold voltage (VT,cc) vs. days after doping for all Lch = 1 μm devices. VT,cc is extracted at a constant current of 10 nA/μm at VDS = −1 V for both forward and backward sweeps. c Drain current (both ID,max at VGS = −3.4 V and Ion at Vov = 1.5 V) vs. days post-doping for all Lch = 1 μm devices. For panels (b, c), a box plot was created for every group of data. The central mark of the box indicates the median, and the bottom and top edges of the box indicate the 25th and 75th percentiles, respectively. d ID vs. VGS curves of an undoped WSe2 device (Lch = 1 μm) at VDS = -1 V initially, then after annealing at 100, 150, and 200 °C. e ID vs. VGS curves of a doped WSe2 device (Lch = 1 μm) at VDS = −1 V initially, then after annealing at 100, 150 and 200 °C. f ID,max at VGS = −3.0 V after various annealing temperatures, for undoped (unfilled diamonds) and doped (filled circles) devices. For the annealing process, the devices are sequentially annealed in vacuum at ~10-4 Torr for 30 min at the given temperature. After annealing, the devices are cooled to room temperature for electrical measurement, then re-annealed at the next temperature.
