Raman and Photocurrent Imaging of Electrical Stress-Induced p–n Junctions in Graphene

Abstract

Electrostatically doped graphene p-n junctions can be formed by applying large source-drain and source-gate biases to a graphene field-effect transistor, which results in trapped charges in part of the channel gate oxide. We measure the temperature distribution in situ during the electrical stress and characterize the resulting p-n junctions by Raman spectroscopy and photocurrent microscopy. Doping levels, the size of the doped graphene segments, and the abruptness of the p-n junctions are all extracted. Additional voltage probes can limit the length of the doped segments by acting as heat sinks. The spatial location of the identified potential steps coincides with the position where a photocurrent is generated, confirming the creation of p-n junctions.

Helicity‐Dependent Photovoltaic Effect in Bi2Se3 Under Normal Incident Light

“…However, graphene monolayers with 2D Dirac states are also known to cause a photocurrent generation in the vicinity of p-n junctions. [51][52][53] In order to further understand the nature of the states involved in the HDP, we performed time resolved magneto-optic Kerr effect (TR-MOKE) measurements on a MBE Bi2Se3 thin film (see Supporting Information S4). In this experiment, a circularly polarized femtosecond optical pulse with a wavelength of 800 nm illuminated the sample at normal incidence.…”

Photocurrent in graphene harnessed by tunable intrinsic plasmons

“…G raphene photodetectors rely on graphene for the absorption of light as well as the generation of an electrical signal through photovoltaic [1][2][3][4][5] , thermoelectric [6][7][8][9] or bolometric [10][11][12] mechanisms. However, the limited absorption in a single layer of graphene through inter-band transitions presents a key challenge 13 .…”

Graphene and Two-Dimensional Materials for Optoelectronic Applications

“…Other possibilities to create p-n junctions in graphene or related 2D materials are chemical doping [35] or by exploiting the work function difference between the intrinsic material (e.g., ∆W = 4.45 eV for graphene [36]) and metal contacts [37][38][39].…”