The forward I-V characteristics of a Schottky diode are commonly used to calculate the ideality factor, saturation current density and barrier height of the Schottky diode which is a majority carrier based device. But if one can obtain some information regarding the minority carriers from reverse bias characteristics?
The Schottky diode is a rectifier contact. Considering a metal-n semiconductor heterojunction, the work function is generally greater for the metal than for the semiconductor. The barrier seen by the electrons in the semiconductor is the contact potential metal-semiconductor, qVco. On the other hand, the potential barrier seen by the electrons within the metal is given by qFB=Wsm-Waf, where Wsm is the metal work function and Waf is the semiconductor electro-affinity. Near the contact, there is a depletion charge zone formed by the ionized donor atoms in the semiconductor. Therefore, the device corresponds to a non-ohmic or rectifier type contact. When the diode is reversed polarized (U
Useful explanation Carlos, Thanks for it. I think only qFB is reported as Schottky barrier height (SBH) in literature. Well, consider two similar Schottky diodes (same material, fabricated in same batch) having different reverse leakage currents, if this is related with their SBH values or some other factors also? For example if series resistance also affects reverse leakage current, if yes, how?
The reverse bias current can be used to determine the schottky barrier hieght given that the substrate doping is low. In case of low doped substrate, the reverse bias current is constant with applied voltage and nearly equal to Is. Again barrier height is not a simple function of work function of metal and semiconductor. It depends on the surface conditions.If you have devices on a sample showing different Is, then they could have slightly different barrier heights.
Series resistance does not show its effect in the reverse bias region. Usually the series resistance of a diode structure is in the range of Ohms. While the resistance offered to current flow in reverse bias will be in the range of several KOhms or Mohms.
Under reverse basing condition one can determine the lifetime in the semiconductor . Which in turn determines the state of impurities of the material.
More interresting in reverse biasing condition is the C-V measurement, it may provide you the doping level and the profile of dopant by changing the voltage. The comparison of the barrier height calculated in reverse mode through the C-V and the barrier height calculated with the I-V in direct mode will give you indications of barrier lowering or traps density at the metal semiconductor interface.
Dear valuable researchers, reverse bias current mainly affected by shunt resistance. The especially in low in injection bias region either at reverse bias current situation dominated by shunt resistance if it exists in the junction, because of diode will be switch off situation so according to Kirchoff law’s most of the current will pass form shunt resistance also similar situation will be at low injection bias region however when the diode becomes conductive (switch on; according to Shockley diode equation) then diode will make a contribution to measured current up to high injection bias condition after the high injection situation then series resistance effect will become dominated due to high current leads to higher voltage drop (potential difference = I.Rs) across the resistance.
Dear Renato Beraldo,
Using your forward bias I-V data graph (plot) semi-log I-V curve (V versus Ln I curve).
If your pn junction diode is not poor you must observe linear curve at forward bias medium injection region. Using this linear curve make extapolation towards to vertical axis (Ln I axis) then intercept point on vertical axis is going to give you information about Is (Io: reverse saturation current). This method catually is same as fitting the experimental curves with the adapted Shockley ideal diode equation.
Dear Abdulkadir Sertap Kavasoglu
Thank you so much for your attention!
I'm a bit confused about the graph and I would like to tight this conception!
First -> I change the linear I-V graph to a Semi-log graph, in this case, I value at log scale.
Second -> Should I change the data (semilog at I) to Ln or the log scale to Ln scale ?
I'm trying to get the SBH from a SiC Schottky Diodes.
Best regards.
Dear Abdulkadir Sertap Kavasoglu .
I got the situation!.
Using your forward bias I-V data graph (plot) semi-log I-V curve (V versus Ln I curve). It means = Semilog graph with Y axis on ln scale. Right?
In some papers, they show only semi-log plot in Y (log 10 base) axis and then, trace a straight line.
In some papers, as you said, they show semilog Y (log e base) plot in Y axis, trace a straight line.
Which case is right?
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