THz direct detector with 2D electron gas periodic structure absorber.

We describe the performance of a direct detector that uses the high mobility 2D electron gas (2DEG) formed at the AlGaAs/GaAs interface as a frequency selective absorber. The 2DEG mesa-structure is etched to form a planar periodic structure with resonant absorption properties in the submm-THz region. Electrons in the 2DEG are heated by incoming radiation above the lattice temperature and the temperature of the hot electrons is measured by Superconducting-2DEG-Superconducting (S-2DEG-S) tunnel junctions. The estimated noise equivalent power for such a detector at 100 mK is in order of 10-₁₈ W/Hz_1/2. In this paper we present the spectral measurements and simulated results of absorption properties at 4.2 K for a resonant mesa geometry. The thermal conductance and time constant of 2D electrons are studied at 450 mK-4.2 K. We measure an electron-phonon conductance on the order of 10-₁₇ W/K per electron at 450 mK which gives a low value of heat conductance 2DEG relative to normal metal absorbers due to the low 2DEG electron density. These devices have a combination of sensitivity and speed which makes them possible candidates for the components in future astrophysical THz instruments.