$V_{\rm th}$ Shift in Single-Layer Graphene Field-Effect Transistors and Its Correlation With Raman Inspection

Abstract

Raman measurement is carried out to understand <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$V_{\rm th}$</tex></formula> shift in single-layer graphene field-effect transistors (GFETs). The G (2D) peak shift in Raman spectra is correlated to the corresponding <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\Delta V_{\rm th}$</tex></formula> during stress and recovery phases. A blue (red) shift of G and 2D peaks is seen during stress (recovery) phase, indicating the corresponding trapping (detrapping) effects in the graphene device. It is interesting to note that, after forming gas annealing <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$(\hbox{H}_{2}/\hbox{Ar})$</tex></formula> , the defects can be generated in graphene (evidenced by D peak of Raman spectra), leading to the increased <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\Delta V_{\rm th}$</tex></formula> for both negative bias temperature instability and positive bias temperature instability in single-layer GFETs.