Investigation of biaxial strain behavior and phonon-limited mobility for γ graphyne: First-principles calculation

γ graphyne is a new allotrope of carbon that has attracted interest because of its semiconductor characteristics and high mobility. This work investigates the biaxial strain behavior and phonon-limited mobility for single-layer γ graphyne by using first-principles calculations. Ab initio molecular dynamics calculations reveal that γ graphyne is thermodynamically stable at 300 K and can withstand a biaxial strain of ε=10%. The mobility is investigated by using the deformation potential method. We consider the contribution to mobility of three equivalent valence-band maxima and conduction-band minima, which correct the prediction of carrier mobility. The mobility significantly decreases with the biaxial strain. When under strain, the effective mass gradually increases and the elastic modulus decreases. The mobility is mainly determined by scattering from acoustic phonons. With increasing strain, optical phonons play a decisive role in carrier scattering. Finally, phonon-limited mobility is investigated by using the electron–phonon coupling method within the framework of the Boltzmann transport equation. At 300 K, the predicted mobility is as high as 9.04×103cm2V−1s−1 for electrons and 8.64×103cm2V−1s−1 for holes. The results thus give the upper limit of γ graphyne’s mobility.