Tuning the Doping Types in Graphene Sheets by N Monoelement

Area of Science:

• Materials Science
• Condensed Matter Physics
• Surface Science

Background:

• Graphene doping is crucial for electronic applications.
• Nitrogen is a common dopant, but its substitutional geometries and effects are not fully understood.
• Controlling doping type and distribution in graphene is a key challenge.

Purpose of the Study:

• To investigate the distinct effects of different nitrogen substitutional geometries in graphene.
• To demonstrate control over graphene doping types using nitrogen monoelement doping.
• To elucidate the relationship between growth conditions and resulting doping characteristics.

Main Methods:

• Chemical vapor deposition (CVD) for graphene synthesis.
• Scanning tunneling microscopy/spectroscopy (STM/STS).
• X-ray/ultraviolet photoelectron spectroscopy (XPS/UPS).
• Hall effect measurements.
• Raman spectroscopy.
• Density functional theory (DFT) calculations.

Main Results:

• Growth conditions, specifically methane partial pressure during CVD, dictate nitrogen's substitutional geometry.
• Low CH4 partial pressure favors pyridinic nitrogen, leading to p-type doping.
• High CH4 partial pressure favors graphitic nitrogen, resulting in n-type doping.
• Pyridinic and graphitic nitrogen atoms segregate into distinct domains within the graphene lattice.

Conclusions:

• Nitrogen monoelement doping offers a versatile method for tuning graphene's electronic properties.
• Understanding and controlling nitrogen's substitutional sites allows for precise p-type and n-type doping.
• This work facilitates the rational design of functional graphene-based materials and devices.