The quasi-free-standing nature of graphene on H-saturated SiC(0001)

TL;DR

This study demonstrates the creation of quasi-free-standing graphene on hydrogen-intercalated SiC(0001), showing improved electronic properties and reduced temperature dependence of mobility, verified through spectroscopy and transport measurements.

Contribution

It provides experimental evidence of hydrogen intercalation converting buffer layer into high-quality graphene with enhanced electronic properties.

Findings

Hydrogen saturates the SiC surface as shown by infrared spectroscopy.

Raman spectra confirm the buffer layer's conversion to graphene with strain and defects.

Graphene exhibits high carrier mobility and reduced temperature dependence.

Abstract

We report on an investigation of quasi-free-standing graphene on 6H-SiC(0001) which was prepared by intercalation of hydrogen under the buffer layer. Using infrared absorption spectroscopy we prove that the SiC(0001) surface is saturated with hydrogen. Raman spectra demonstrate the conversion of the buffer layer into graphene which exhibits a slight tensile strain and short range defects. The layers are hole doped (p = 5.0-6.5 x 10^12 cm^(-2)) with a carrier mobility of 3,100 cm^2/Vs at room temperature. Compared to graphene on the buffer layer a strongly reduced temperature dependence of the mobility is observed for graphene on H-terminated SiC(0001)which justifies the term "quasi-free-standing".