Heat capacity of nonequilibrium electron-hole plasma in graphene layers and graphene~bilayers

TL;DR

This paper investigates the heat capacity of nonequilibrium electron-hole plasma in graphene layers and bilayers, revealing temperature-dependent values that differ from classical expectations, with implications for high-speed device optimization.

Contribution

It provides a detailed analysis of the heat capacity in graphene structures under nonequilibrium conditions, highlighting differences from classical models and potential device applications.

Findings

GL heat capacity is approximately 6.58 at weak pumping.

GBL heat capacity varies from 2.37 to 6.58 with temperature.

Values differ significantly from classical 2D carrier heat capacity of 1.

Abstract

We analyze the statistical characteristics of the quasi-nonequilibrium two-dimensional electron-hole plasma in graphene layers (GLs) and graphene bilayers (GBLs) and evaluate their heat capacity.The GL heat capacity of the weakly pumped intrinsic or weakly doped GLs normalized by the Boltzmann constant is equal to $c_{GL} \simeq 6.58$. With varying carrier temperature the intrinsic GBL carrier heat capacity $c_{GBL}$ changes from $c_{GBL} \simeq 2.37$ at $T \lesssim 300$~K to $c_{GBL} \simeq 6.58$ at elevated temperatures. These values are markedly differentfrom the heat capacity of classical two-dimensional carriers with $c = 1$. The obtained results can be useful for the optimization of different GL- and GBL-based high-speed devices.