ELECTRON-TEMPERATURE IN LOW-DIMENSIONAL WIRES USING THERMAL NOISE MEASUREMENTS

We have studied electric field heating of low-dimensional electrons in GaAs/AlGaAs heterostructures at 4.2 K using thermal noise measurement s. For the two-dimensional (2D) wire, the increase in electron tempera ture, Delta T-e, extracted from noise measurements is in agreement wit h previous measurements of Delta T-e and is explained by emission of a coustic and optical phonons. Measurements are extended to quasi-one-di mensional (Q1D) wires which are shorter than the 2D wires. In these Q1 D wires, we find that for small Delta T-e, power dissipation is more e ffective than in the 2D wires, due to additional energy relaxation thr ough the contacts. This effect is most pronounced in the highest mobil ity wire where the energy relaxation length is the longest. (C) 1995 A merican Institute of Physics.