Interface Trap Suppression and Electron Doping in Van der Waals Materials Using Cross-Linked Poly(vinylpyrrolidone)

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Van der Waals (vdW) materials exhibit instability in ambient conditions, undergoing spontaneous degradation.
• Existing passivation methods often hinder crucial charge transfer doping by blocking carrier injection.
• Tungsten diselenide (WSe2) is a prominent vdW material susceptible to air instability and requires effective stabilization.

Purpose of the Study:

• To develop a facile method for stabilizing and doping WSe2.
• To investigate the effect of poly(vinylpyrrolidone) (PVP) coating on WSe2 stability and electronic properties.
• To explore the potential of PVP as a doping and defect passivation agent for vdW materials.

Main Methods:

• Coating of WSe2 field-effect transistors (FETs) with poly(vinylpyrrolidone) (PVP).
• Characterization of carrier type conversion from p-type to n-type.
• Quantification of changes in interface trap density related to Se vacancies.

Main Results:

• PVP coating successfully converted the major carrier type of WSe2 FETs from hole (p-type) to electron (n-type).
• The method effectively mediated Selenium (Se) vacancies in WSe2.
• Vacancy-induced interface trap density was reduced by approximately 500 times, indicating significant defect passivation.

Conclusions:

• Poly(vinylpyrrolidone) (PVP) offers a practical and effective approach for n-doping and defect passivation of van der Waals (vdW) materials like WSe2.
• This technique overcomes the limitations of conventional passivation methods by enabling carrier injection.
• The study provides valuable insights into the chemical interactions and electronic transport mechanisms in doped and passivated vdW materials.