The surface oxidation effect on photocurrent in WSe_1.95Te_0.05 nanosheets

Area of Science:

• Materials Science
• Photovoltaics
• Nanotechnology

Background:

• Transition metal dichalcogenides (TMDs) like WSe2 are promising for optoelectronic applications.
• Surface oxidation can significantly alter the electronic and optical properties of 2D materials.
• Understanding these changes is crucial for device stability and performance.

Purpose of the Study:

• To investigate the effect of surface oxidation on the photocurrent response of WSe1.95Te0.05 nanosheets.
• To analyze the wavelength-dependent photocurrent behavior and its correlation with incident photon-to-current efficiency (IPCE).
• To elucidate the role of the oxidized layer (WO3) in the observed phenomena.

Main Methods:

• Fabrication and characterization of WSe1.95Te0.05 nanosheets.
• Measurement of photocurrent response under varying light wavelengths (405 nm, 532 nm, 808 nm).
• Analysis of incident photon-to-current efficiency (IPCE) spectra.
• Spectroscopic analysis to identify surface oxidation products.

Main Results:

• Surface oxidation of WSe1.95Te0.05 nanosheets was confirmed, leading to the formation of WO3.
• A distinct wavelength-dependent photocurrent response was observed: enhanced at 405 nm, unchanged at 532 nm, and suppressed at 808 nm.
• The observed photocurrent trends correlated with changes in absorbance and were linked to the wavelength-dependent IPCE of the WO3 layer.

Conclusions:

• Surface oxidation significantly modifies the photocurrent responsibility of WSe1.95Te0.05 nanosheets.
• The formation of WO3 is responsible for the wavelength-dependent photocurrent and IPCE.
• These findings highlight the importance of surface chemistry in the performance and stability of WSe2-based photodetectors.