Differential tunnel transparency of a rectangular heterostructural barrier for the terahertz frequency range

Electron wave tunneling through a rectangular heterostructural emitter barrier is considered in the case of a homogeneous high-frequency (hf) alternating electric field directed normal to the barrier interfaces. This hf field leads not only to the well-known increase in a stationary tunnel current through the emitter barrier, which is proportional to EB2 (where EB is the electric-field amplitude) but also to a linear (∼EB) increase in an alternating current (ac) through this barrier with the same frequency ω as the electric-field frequency. The ac is a sharp function of ω, which grows significantly with an increase in ω (typically in the terahertz range). In a certain intermediate current and frequency region, the above-mentioned increase in the ac is the dominating effect of the alternating field. Such an effect can be used to optimize tunnel barrier emitters for ballistic transit-time terahertz-range oscillators.