Revealing the Active Role of the Gate Electrode in Weak-Light Detection.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41784142.
- Also identified by DOI 10.1021/acsnano.5c13029 and PMC identifier 13001079.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The contribution of gate materials to the photoresponse of thin-film field-effect photodetectors has long been overlooked, with prior studies focusing primarily on photoconductive and photogating effects within the sensing layer. Here, we show that under weak illumination, photocarriers primarily originate from the silicon gate rather than the MoS<sub>2</sub> channel. Absorption spectra confirm that light is mainly absorbed by the gate, driving a negative photocurrent (NPC). The NPC magnitude and slope vary with illumination intensity and <i>V</i><sub>DS</sub>, suggesting transport dominated by Si/SiO<sub>2</sub> interface traps. NPC persists when MoS<sub>2</sub> is replaced with Au/Ti, reinforcing the gate-driven mechanism. At higher powers, band bending reverses due to competing photovoltaic and trap-induced potentials. These results highlight the active role of the gate and offer strategies for device optimization.