Unbiased continuous wave terahertz photomixer emitters with dis-similar Schottky barriers

We are introducing a new bias free CW terahertz photomixer
emitter array. Each emitter consists of an asymmetric metal-semiconductormetal (MSM) that is made of two side by side dis-similar Schottky contacts,
on a thin layer of low temperature grown (LTG) GaAs, with barrier heights
of difference (ΔΦB) and a finite lateral spacing (s). Simulations show that
when an appropriately designed structure is irradiated by two coherent optical beams of different center wavelengths, whose frequency difference (∆f)
falls in a desired THz band, the built-in field between the two dis-similar
potential barriers can accelerate the photogenerated carriers that are modulated by ∆ω, making each pitch in the array to act as a CW THz emitter, effectively. We also show the permissible values of s and ΔΦB pairs, for
which the strengths of the built-in electric field maxima fall below that of
the critical of 50 V/μm— i.e., the breakdown limit for the LTG-GaAs layer.
Moreover, we calculate the THz radiation power per emitter in an array.
Among many potential applications for these bias free THz emitters their
use in endoscopic imaging without a need for hazardous external biasing
circuitry that reduces the patient health risk, could be the most important
one. A hybrid numerical simulation method is used to design an optimum
emitter pitch, radiating at 0.5 THz.