Phonon-limited Diffusion Thermopower in Graphene

Phonon-limited diffusion thermopower,

S

d

, of graphene is studied, for 10 < T < 300 K taking into account the influence of substrate. The electrons are assumed to be scattered by the acoustic phonons (APs), optical phonons as well as the surface optical phonons (SOPs). The first order perturbation distribution function

ϕ

(

E

), as a function of carrier energy

E

, is computed by directly solving the linearized Boltzmann equation using the iteration technique. Numerical calculations of energy dependence of

ϕ

(

E

), bring out the characteristics of phonon scattering mechanisms. Determined mainly by APs at low temperatures and then by SOPs,

S

d

for SiO

2

substrate is found to increase with T reaching a room temperature value of ~30 μV/K.