Monolayer WS2 crossed with an electro-spun PEDOT-PSS nano-ribbon: Fabricating a Schottky diode

Abstract

WS 2 and PEDOT-PSS were individually characterized with the goal of analyzing charge transport across a hetero-junction formed by these two materials. In thermal equilibrium electron flow from the WS 2 conduction band into the polymer LUMO level leads to band bending that creates a potential barrier preventing further current. The measured current-voltage (I DS -V DS ) curve across the hetero-junction was non-linear and asymmetric similar to a diode, with a turn-on voltage of 1.4V and a rectification ratio of 12. The device I-V data were analyzed using the standard thermionic emission model of a Schottky junction and yielded an ideality parameter of 1.9 and a barrier height of 0.58 eV. This facile technique is the first report on a nano-diode fabricated using WS 2 and PEDOT-PSS, opening up the possibility of extending this work to include other layered transition metal dichalcogenides and conducting polymers.

Rectifying effect in a MoS2 monolayer crossed with an electro-spun PEDOT-PSS nano-ribbon

“…The Fermi level in PEDOT-PSS (E FP ) is assumed to stay pinned midway between the LUMO and HUMO levels. The nanoribbon conductivity was 0.23 S/cm, lower than reported earlier [16] due to a slightly larger fraction of PEO in the present composite nano-ribbon. The lower conductivity, however, does not affect diode operation.…”

“…Also, being a majority carrier device, Schottky diodes lack diffusion capacitance and hence can operate at higher frequencies [15]. Recently, we fabricated and analyzed a Schottky diode by crossing monolayer n-WS 2 with a poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid)-PEDOT-PSS nano-ribbon [16]. This paper extends the previous work to include a similar device, where monolayer MoS 2 is crossed with a PEDOT-PSS nano-ribbon.…”

Rectify Effect of Pedot:PSS/WS2 Heterostructure

“…On the basis of literature and our results, it was noticed that the Schottky junction was formed by Pedot:PSS and WS 2 at all temperatures. Pedot:PSS is a conducting polymer and does not show field effect (in this case, it can be seen as a metal) and WS 2 is a n‐type semiconductor.…”

“…Here I s is the saturation current, q is the electron charge, V is the applied voltage, T is the absolute temperature, n is the ideality factor, k is the Boltzmann's constant, A is the contact area, A ** is the effective Richardson constant (120 cm −2 K −2 for n‐WS 2 ), and φ is the Schottky barrier height. The effective constant A ** is known and the I – V measurement was made to determine the saturation current I s .…”

“…By Equation , the calculated values of φ is plotted as a function of back‐gate voltage bias at room temperature. It is observed that the barrier height of the Schottky diode is strongly depending on the applied back‐gate voltage bias.…”