 Tunnel diode schematic symbol A tunnel diode or Esaki diode is a type of semiconductor diode which is capable of very fast operation, well into the microwave region GHz, by utilizing quantum mechanical effects. Image File history File links Tunnel_diode_symbol. ...
Image File history File links Tunnel_diode_symbol. ...
It has been suggested that Peak Inverse Voltage be merged into this article or section. ...
A semiconductor is a solid whose electrical conductivity is in between that of a conductor and that of an insulator, and can be controlled over a wide range, either permanently or dynamically. ...
A gigahertz is a billion hertz or a thousand megahertz, a measure of frequency. ...
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It was named after Leo Esaki, who in 1973 received the Nobel Prize in Physics for discovering the electron tunneling effect used in these diodes. Leo Esaki, born Leona Esaki [1] (江崎 玲於奈 Esaki Reona, born March 12, 1925) is a Japanese physicist who shared the Nobel Prize in Physics in 1973 with Ivar Giaever and Brian David Josephson for his discovery of the phenomenon of electron tunneling. ...
Quantum tunneling is the quantum-mechanical effect of transitioning through a classically-forbidden energy state. ...
These diodes have a heavily doped p-n junction only some 10 nm (100 Å) wide. The heavy doping results in a broken bandgap, where conduction band electron states on the n-side are more or less aligned with valence band hole states on the p-side. A p-n junction is formed by combining N-type and P-type semiconductors together in very close contact. ...
An ångström or aangstroem (the official transliteration), or angstrom (symbol Å) is a non-SI unit of length that is internationally recognized, equal to 0. ...
In solid state physics and related applied fields, the band gap is the energy difference between the top of the valence band and the bottom of the conduction band in insulators and semiconductors. ...
In semiconductors and insulators, the conduction band is the range of electron energy, higher than that of the valence band, sufficient to make the electrons free to accelerate under the influence of an applied electric field and thus constitute an electric current. ...
Electron atomic and molecular orbitals In atomic physics and quantum chemistry, the electron configuration is the arrangement of electrons in an atom, molecule, or other physical structure (, a crystal). ...
In solids, the valence band is the highest range of electron energies where electrons are normally present at zero temperature. ...
For the following two reasons the electron hole was introduced into calculations: If an electron is excited into higher state it leaves a hole in its old state. ...
Forward bias operation
Under normal forward bias operation, as voltage begins to increase, electrons at first tunnel through the very narrow p-n junction barrier because filled electron states in the conduction band on the n-side become aligned with empty valence band hole states on the p-side of the pn junction. As voltage increases further these states become more misaligned and the current drops — this is called negative resistance, because current decreases with increasing voltage. As voltage increases yet further, the diode begins to operate as a normal diode, where electrons travel by conduction across the pn junction, and no longer by tunneling through the pn junction barrier. Thus the most important operating region for a tunnel diode is the negative resistance region. Properties The electron (also called negatron, commonly represented as e−) is a subatomic particle. ...
A VI curve with a negative differential resistance region Negative resistance or negative differential resistance (NDR) is a property of electrical circuit elements composed of certain materials in which, over certain voltage ranges, current is a decreasing function of voltage. ...
Reverse bias operation When used in the reverse direction they are called back diodes and can act as fast rectifiers with zero offset voltage and extreme linearity for power signals. (That is, they have an accurate square law characteristic in the reverse direction.) A rectifier is one or more diodes arranged for converting alternating current (AC) to direct current (DC). ...
Under reverse bias filled states on the p-side become increasingly aligned with empty states on the n-side and electrons now tunnel through the pn junction barrier in reverse direction — this is the Zener effect that also occurs in zener diodes. A p-n junction is formed by combining N-type and P-type semiconductors together in very close contact. ...
Zener diode schematic symbol A Zener diode is a type of diode that permits current to flow in the forward direction like a normal diode, but also in the reverse direction if the voltage is larger (not equal to, but larger) than the rated breakdown voltage known as Zener knee...
Technical comparisons
 A rough approximation of the VI curve for a tunnel diode, showing the negative differential resistance region In a conventional semiconductor diode, conduction takes place while the PN junction is forward biased and blocks current flow when the junction is reverse biased. This occurs up to a point known as the 'reverse breakdown voltage' when conduction begins (often accompanied by destruction of the device). In the tunnel diode, the dopant concentration in the P and N layers are increased to the point where the reverse breakdown voltage becomes zero and the diode conducts in the reverse direction. However, when forward-biased, an odd effect occurs called 'quantum mechanical tunnelling' which gives rise to a region where an increase in forward voltage is accompanied by a decrease in forward current. This negative resistance region can be exploited in a solid state version of the dynatron oscillator which normally uses a tetrode thermionic valve (or tube). Image File history File links Download high resolution version (900x900, 41 KB) Negative differential resistance plot, such as in a Gunn diode. ...
Image File history File links Download high resolution version (900x900, 41 KB) Negative differential resistance plot, such as in a Gunn diode. ...
Quantum tunneling is the quantum-mechanical effect of transitioning through a classically-forbidden energy state. ...
A VI curve with a negative differential resistance region Negative resistance or negative differential resistance (NDR) is a property of electrical circuit elements composed of certain materials in which, over certain voltage ranges, current is a decreasing function of voltage. ...
In theory, if a perfect charged capacitor is connected in parallel with a perfect inductor, the circuit will oscillate forever as the energy is transferred back and forth between the capacitor and the inductor. ...
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In electronics, a vacuum tube (American English) or (thermionic) valve (British English) is a device generally used to amplify a signal. ...
The tunnel diode showed great promise as an oscillator and high-frequency threshold (trigger) device since it would operate at frequencies far greater than the tetrode would, in fact well into the microwave bands. However, since its discovery, more conventional semiconductor devices have surpassed its performance using conventional oscillator techniques. This article is about the type of Electromagnetic radiation. ...
Tunnel diodes are also relatively resistant to nuclear radiation, as compared to other diodes. This makes them well suited to higher radiation environments, such as those found in space applications. Microelectronics designed for environments with high levels of ionizing radiation have special design challenges. ...
Radiation hazard symbol. ...
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