A resonant tunnel diode is a semiconductor element of an electrical circuit with a nonlinear current-voltage characteristic that uses carrier tunneling through a potential well surrounded by two potential barriers.
The resonant tunnel diode has a portion of the current-voltage characteristic with negative differential conductivity .
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In the resonant tunnel diode a heterostructure is used, in which the potential well for charge carriers, for example, for electrons, is separated from the contact doped regions by potential barriers. For example, the potential well region can consist of GaAs, the potential barrier region can consist of Ga 1-x Al x As, the outer regions can be doped with GaAs donors.
Principle of action
With a high probability, only those electrons pass through the heterostructure, whose energy coincides with the energy of quantized levels in the potential well. Electrons with more or less energy cannot pass through the structure. As the voltage applied to the heterostructure increases, the electron energy in the contact layer increases. When it becomes equal to the energy of the quantized level inside the well, an electric current begins to flow through the structure. However, with a further increase in the voltage on the diode, the electrons gain more energy and again cannot pass through the heterostructures — the current drops. As a consequence, a region of negative differential conductivity arises.
Use
The negative differential conductance of a resonant tunnel diode is used to create high-frequency oscillators of electrical oscillations. The frequencies of such generators can reach the terahertz range.
See also
- Diode
- Tunnel diode