Millimeter and sub-millimeter heterodyne mixing based on 2DEG hot-electron bolometers

We investigate GHz and THz heterodyne mixer based on the electron heating effect of a two-dimensional electron gas (2DEG) by electromagnetic radiation at liquid nitrogen temperatures (77K). The devices are fabricated from AlGaAs/GaAs heterostructures with a channel width of 150 $\mu $m and lengths varying from 3-20 $\mu $m. Steady-state measurements are used to investigate electron heating in these devices and determine basic parameters, such as electron-phonon energy relaxation time and electron heat capacity. We perform mixing experiments at $\sim $100 GHz frequency range with two Gunn diodes as the radiation sources, and find that electron heating is the primary mixing mechanism at these frequencies. For the mixing experiments at $\sim $ 2 terahertz range, a quantum cascade laser (QCL) is employed as the local oscillator. To optimize our device, we also investigate electron kinetics and transport properties in the 2DEG hot-electron bolometer.