Carrier Multiplication via Photocurrent Measurements in Dual-Gated MoTe_2

TL;DR

This study demonstrates carrier multiplication in dual-gated MoTe2 through photocurrent measurements, confirming multiple electron-hole pair generation and potential for surpassing solar cell efficiency limits.

Contribution

It introduces a simple photocurrent measurement method to observe carrier multiplication in MoTe2, clarifying optical interpretation complexities.

Findings

Photocurrent increases with excitation energy.

Quantum efficiency exceeds 2Eg, indicating carrier multiplication.

Potential to surpass Shockley-Queisser limit.

Abstract

Although van der Waals layered transition metal dichalcogenides from transient absorption spectroscopy have successfully demonstrated an ideal carrier multiplication (CM) performance with an onset of nearly 2Eg,interpretation of the CM effect from the optical approach remains unresolved owing to the complexity of many-body electron-hole pairs. We demonstrate the CM effect through simple photocurrent measurements by fabricating the dual-gate P-N junction of a MoTe2 film on a transparent substrate. Electrons and holes were efficiently extracted by eliminating the Schottky barriers in the metal contact and minimizing multiple reflections. The photocurrent was elevated proportionately to the excitation energy. The boosted quantum efficiency confirms the multiple electron-hole pair generation of >2Eg, consistent with CM results from an optical approach, pushing the solar cell efficiency beyond the Shockley-Queisser limit.