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Under reverse bias, the diode equation's exponential term is near 0, so the current is near the somewhat constant reverse current value (roughly a picoampere for silicon diodes or a microampere for germanium diodes, [1] although this is obviously a function of size).
A silicon p–n junction in reverse bias. Connecting the p-type region to the negative terminal of the voltage supply and the n-type region to the positive terminal corresponds to reverse bias. If a diode is reverse-biased, the voltage at the cathode is comparatively higher than at the anode. Therefore, very little current flows until the diode ...
Under zero- or reverse-bias (the "off" state), a PIN diode has a low capacitance. The low capacitance will not pass much of an RF signal. Under a forward bias of 1 mA (the "on" state), a typical PIN diode will have an RF resistance of about 1 ohm, making it a good conductor of RF. Consequently, the PIN diode makes a good RF switch.
The Shockley ideal diode equation or the diode law (named after the bipolar junction transistor co-inventor William Bradford Shockley) models the exponential current–voltage (I–V) relationship of diodes in moderate forward or reverse bias. The article Shockley diode equation provides details.
Using the Shockley equation, the small-signal diode resistance of the diode can be derived about some operating point where the DC bias current is and the Q-point applied voltage is . [6] To begin, the diode small-signal conductance g D {\displaystyle g_{D}} is found, that is, the change in current in the diode caused by a small change in ...
In this case, the net current flows from the P-side to the N-side. The carrier density is large (it varies exponentially with the applied bias voltage), making the junction conductive and allowing a large forward current. [3] The mathematical description of the current is provided by the Shockley diode equation.
Band-bending for p–n diode in reverse bias Quasi-Fermi levels in reverse-biased p–n diode. In reverse bias the occupancy level for holes again tends to stay at the level of the bulk p-type semiconductor while the occupancy level for electrons follows that for the bulk n-type. In this case, the p-type bulk band edges are raised relative to ...
Reverse leakage current in a semiconductor device is the current when the device is reverse biased.. Under reverse bias, an ideal semiconductor device should not conduct any current, however, due to attraction of dissimilar charges, the positive side of the voltage source draws free electrons (majority carriers in the n-region) away from the P-N junction.