Experimental evidence of disorder enhanced electron-phonon scattering in graphene devices

The heat equation for nanoconstrictions in 2D materials with Joule self-heating

“…Electrical and thermal transport were considered in the classical, diffusive regime, applicable to experiments at room temperature or above, and with spatial dimensions typically of the order of 100 nm or above [18][19][20][21]38]. At lower temperatures, with smaller devices, and depending on sample quality, it is necessary to consider ballistic transport [4,[75][76][77][78] and, possibly, quantum interference effects.…”

“…There is huge interest in the thermal properties of twodimensional (2D) materials, motivated by applications to thermal management [1][2][3][4], interconnects in integrated circuits [5][6][7], thermoelectric devices [8][9][10][11] and nanoscale fabrication [12][13][14][15]. While nanoscale constrictions are of great importance for their electrical transport characteristics, particularly in the quantum regime [16,17], they also promote enhanced Joule self-heating and thermoelectric coefficients [18][19][20][21]. For such structures, scanning thermal microscopy [4] is an ideal tool to map surface temperatures with spatial resolution of a few nanometres, as applied to carbon nanotubes [22], nanowires [23][24][25][26] and 2D materials [20,21,[27][28][29][30][31][32][33][34][35][36][37].…”

“…While nanoscale constrictions are of great importance for their electrical transport characteristics, particularly in the quantum regime [16,17], they also promote enhanced Joule self-heating and thermoelectric coefficients [18][19][20][21]. For such structures, scanning thermal microscopy [4] is an ideal tool to map surface temperatures with spatial resolution of a few nanometres, as applied to carbon nanotubes [22], nanowires [23][24][25][26] and 2D materials [20,21,[27][28][29][30][31][32][33][34][35][36][37].…”

“…We consider three geometries as typical examples, figure 1, which are a rectangle, a nanowire [18,19,[23][24][25][26][49][50][51] of constant width w, and a bow tie (or wedge) constriction [20,21,[51][52][53] of varying width down to a minimum w. We compare the temperature profiles for devices with the same macroscopic dimensions and characteristic parameters, for either a fixed applied potential difference or a fixed current. The nanowire and bow tie are excellent representative examples because they exhibit markedly different behaviour: the electrical resistances of the nanowire and bow tie have different dependences on the width w, and this means that Joule heating is independent of w for the nanowire (for small w and (4).…”

Electric-field-driven conductance switching in encapsulated graphene nanogaps

“…To study the effect of electric breakdown on the encapsulation layer, we have imaged devices using atomic force microscopy both before and after electric breakdown and found that the 100 nm thick silica-like top layer is not removed by the electric breakdown of the graphene underneath, despite the high temperatures reached during breakdown -in excess of 1000K [8,27]. Figure 3 shows height profiles on the constrictions.…”