Lithium-ion conducting glass ceramics for electrostatic gating

TL;DR

This paper demonstrates the use of lithium-ion conducting glass ceramics as solid electrolytes for electrostatic gating in WSe2 transistors, offering advantages over liquid gating methods and enabling new experiments with exposed semiconductor surfaces.

Contribution

The study introduces solid electrolyte gating with lithium-ion conductors for 2D transistors, providing a simpler, more accessible alternative to ionic liquids and enabling direct light emission detection.

Findings

Devices operate similarly to ionic liquid gates for negative voltages

Strong electroluminescence observed in WSe2 monolayers under certain conditions

Solid electrolytes enable easier light detection compared to liquid gates

Abstract

We explore solid electrolytes for electrostatic gating using field-effect transistors (FETs) in which thin WSe$_2$ crystals are exfoliated and transferred onto a lithium-ion conducting glass ceramic substrate. For negative gate voltages ($V_G < 0$) the devices work equally well as ionic liquid gated FETs while offering specific advantages, whereas no transistor action is seen for $V_G>0$. For $V_G <0$ the devices can nevertheless be driven into the ambipolar injection regime by applying a large source-drain bias, and strong electroluminescence is observed when direct band-gap WSe$_2$ monolayers are used. Detecting and imaging the emitted light is much simpler in these FETs as compared to ionic liquid gated transistors, because the semiconductor surface is exposed (i.e., not covered by another material). Our results show that solid electrolytes are complementary to existing liquid gates, as they enable experiments not possible when the semiconductor is buried under the liquid itself.