Monte Carlo simulation of THz radiation detection in GaAs n+ nn+ diodes with inhomogeneously doped n-region

A proper profile of nonuniform doping of GaAs n+ nn+ structure to reach the maximum detection sensitivity is proposed. It is shown that the main role in formation of longitudinal transport asymmetry and THz radiation detection is played by optical phonon emission process. It is found that the detection current independs of frequency in spectral range 0.02-1 THz, reaches maximum near 2.2 THz (10 and 80 K) or 3 THz (300 K) and then becomes to decrease due to the inertia of optical phonon emission process.