Competing Channels for Hot Electron Cooling in Graphene

Abstract

We report on temperature dependent photocurrent measurements of high-quality dual-gated monolayer graphene (MLG) p-n junction devices. A photothermoelectric (PTE) effect governs the photocurrent response in our devices, allowing us to track the hot electron temperature and probe hot electron cooling channels over a wide temperature range (4 K to 300 K). At high temperatures ($T>T^{\ast }$), we found that both the peak photocurrent and the hot spot size decreased with temperature, while at low temperatures ($T<T^{\ast }$), we found the opposite, namely that the peak photocurrent and the hot spot size increased with temperature. This non-monotonic temperature dependence can be understood as resulting from the competition between two hot electron cooling pathways: (a) (intrinsic) momentum-conserving normal collisions (NC) that dominates at low temperatures and (b) (extrinsic) disorder-assisted supercollisions (SC) that dominates at high temperatures. Gate control in our high quality samples allows us to resolve the two processes in the same device for the first time. The peak temperature $T^{\ast }$ depends on carrier density and disorder concentration, thus allowing for an unprecedented way of controlling graphene's photoresponse.

5 pages, 4 figures

References in corpus (9)

• Thermoelectric and Magnetothermoelectric Transport Measurements of Graphene
• Transport measurements across a tunable potential barrier in graphene
• Photo-excitation Cascade and Multiple Carrier Generation in Graphene
• Substrate limited electron dynamics in graphene
• Electronic transport and quantum Hall effect in bipolar graphene p-n-p junction
• Electron-phonon heat transfer in monolayer and bilayer graphene
• Supercollision cooling in undoped graphene
• Surface polar optical phonon interaction induced many-body effects and hot-electron relaxation in graphene
• Energy-driven Drag at Charge Neutrality in Graphene

Cited by in corpus (15)

• Hydrodynamics of electrons in graphene
• Hot carriers in graphene -- fundamentals and applications
• Hot-carrier photocurrent effects at graphene-metal interfaces
• Hot-electron cooling by acoustic and optical phonons in monolayers of MoS${}_2$ and other transition-metal dichalcogenides
• Thermoelectric graphene photodetectors with sub-nanosecond response times at Terahertz frequencies
• Energy Flows in Graphene: Hot Carrier Dynamics and Cooling
• Plasmonic graphene photodetector based on channel photo-thermoelectric effect
• Hot-Carrier Seebeck Effect: Diffusion and Remote Detection of Hot Carriers in Graphene
• Plasmon-enhanced graphene photodetector with CMOS-compatible titanium nitride
• Tunable Ultrafast Thermal Relaxation in Graphene Measured by Continuous-Wave Photomixing
• High-Performance All-Optical Modulator Based on Graphene-hBN Heterostructures
• Abrupt p-n junction using ionic gating at zero-bias in bilayer graphene
• Ultra-Efficient DC-gated all-optical graphene switch
• Disorder-assisted Robustness of Ultrafast Cooling in High Doped CVD-Graphene
• Giant intrinsic photoresponse in pristine graphene