First-principles Analysis of Photo-current in Graphene PN Junctions

TL;DR

This study uses first-principles methods to analyze photocurrent generation in graphene PN junctions, revealing broad spectral response and polarization dependence, with insights into chemically doped and gate-controlled devices.

Contribution

It introduces a combined NEGF and DFT approach to investigate photocurrent in graphene PN junctions formed by doping or gating, highlighting their spectral and polarization characteristics.

Findings

Broad band photo-response including terahertz range

Response depends on light polarization angle

Chemically doped and gate-controlled junctions show similar properties

Abstract

We report a first principles investigation of photocurrent generation by graphene PN junctions. The junctions are formed by either chemically doping with nitrogen and boron atoms, or by controlling gate voltages. Non-equilibrium Green's function (NEGF) formalism combined with density functional theory (DFT) is applied to calculate the photo-response function. The graphene PN junctions show a broad band photo-response including the terahertz range. The dependence of the response on the angle between the light polarization vector and the PN interface is determined. Its variation against photon energy $E_{ph}$ is calculated in the visible range. The essential properties of chemically doped and gate-controlled PN junctions are similar, but the former shows fingerprints of dopant distribution.