PHT.301 Physics of Semiconductor Devices | |
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Schottky diode IV characteristicsA Schottky contact is formed when a metal is deposited on a semiconductor. The current-voltage characteristic of a Schottky diode has the same form as that for a pn-diode, I=IS(exp(eVηkBT)−1)[A].Here I is the current, IS is the saturation current, e is the charge of an electron, V is the voltage, kB is Boltzmann's constant, T is the absolute temperature, and η is the nonideality factor where typically η=1 for a Schottky diode. It is sometimes said that a Schottky diode turns on at a lower voltage than a pn-diode, but the equation for the two types of diodes is the same. The difference is that Schottky diodes typically have a much larger saturation current IS so the current of a Schottky diode is much larger for the same voltage. For a real diode there is always a resistance RS in series. This modifies the diode equation to, I=IS(exp(e(V−IRS)ηkBT)−1)[A].This complicates the calculation since I now appears on both sides of the equation. However, such equations can be solved numerically, for instance by using a binary search. For a Schottky diode, the saturation current can be written as, IS=Aem∗k2B2π2ℏ3T2exp(−ϕbkBT).Here A is the area of the Schottky diode perpendicular to the current flow, m∗ is the effective mass, ϕb is the energy between the Fermi energy of the metal and the conduction band of the semiconductor at the interface called the Schottky barrier height and T the temperature.
IS= 8.83e-7 [A];
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