A comparative study of transport properties of monolayer graphene and AlGaN-GaN heterostructure

M D Ozdemir,M Ozdemir,O Atasever,Z Yarar,B Ozdemir

doi:10.1063/1.4926341

M D Ozdemir, M Ozdemir + Show 3 more

Open Access

https://doi.org/10.1063/1.4926341

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Abstract

The electronic transport properties of monolayer graphene are presented with an Ensemble Monte Carlo method where a rejection technique is used to account for the occupancy of the final states after scattering. Acoustic and optic phonon scatterings are considered for intrinsic graphene and in addition, ionized impurity and surface roughness scatterings are considered for the case of dirty graphene. The effect of screening is considered in the ionized impurity scattering of electrons. The time dependence of drift velocity of carriers is obtained where overshoot and undershoot effects are observed for certain values of applied field and material parameters for intrinsic graphene. The field dependence of drift velocity of carriers showed negative differential resistance and disappeared as acoustic scattering becomes dominant for intrinsic graphene. The variation of electron mobility with temperature is calculated for intrinsic (suspended) and dirty monolayer graphene sheets separately and they are compared. These are also compared with the mobility of two dimensional electrons at an AlGaN/GaN heterostructure. It is observed that interface roughness may become very effective in limiting the mobility of electrons in graphene.

Highlights

Graphene, a truely two dimensional material with a linear energy dispersion without any gap is synthesized for the first time by Novoselov et al.[1]
The carrier transport problem is investigated for an intrinsic graphene sample by an ensemble Monte Carlo (MC) technique in Ref. 15 where acoustic and optic phonon scatterings are taken into account
All results shown here are at T = 300 K where the acoustic deformation potential constant is Dac = 3.7 eV and the optic deformation constant is taken to be Do = 1 × 109 eV/cm

Summary

INTRODUCTION

A truely two dimensional material with a linear energy dispersion without any gap is synthesized for the first time by Novoselov et al.[1]. In the present study we investigate the charge transport and mobility charactheristics of monolayer graphene as a function of temperature and various material parameters using an ensemble MC method. We consider both the so called dirty graphene with impurities and an intrinsic graphene. Conductivity calculations are carried out in the presence of scattering mechanisms just mentioned for various material parameters and from these the mobility of carriers are determined These mobility values are compared with that of a two dimensional electron gas confined at an AlGaN/GaN heterostructure.

Scattering Mechanisms

Ensemble Monte Carlo

RESULTS AND DISCUSSIONS

CONCLUSIONS