One of my problems is to fully understand the principle of the space charge limited current model.
- the process of trapping: after the ohmic region, at the point where the concentration of free carriers in the insulating material (in my case GaN with a relativly huge bandgap) matches the concentration of injected carriers, the current transport is limited by trapping, right? How can I understand this process? The double logarithmic scale shows a V^2 slope in this region, so it's obvious that this corresponds with a space charge, which is built up. Do these (I think for small voltages we are talking about shallow traps) traps work like a "cage" which catches these carriers and thus limits the current? But why can I observe a quadratic beahviour then?
- at Vtfl all these traps can be filled. In an energetic point of view, do I understand this right, that the ferminiveau "crosses" the energy-niveau of these traps and thus the traps are (statistically) all filled up and stay filled? So every additional injected carrier is able to "go over" these traps because they are filled? Is that the (or a) reason for the steep increase in current (slope above 2)?
- What kind of impact do the deep traps have?
Thank you
Space charge limited conduction is observed at high electric field due to injection of charge carriers from electrodes. A super ohmic behaviour is observed in this situation.SCLC will be observed in those materials only where the density of thermally generated charge carriers is much smaller than injected charge carriers. current vs voltage curve is different for different situation, no traps, single trap level, uniform trap distribution, exponential trap distribution.Squire dependence on voltage is observed when no traps are present.For other trap distribution ln I vs ln V curve show different slope which is temperature dependent also. For detailed theory go through the book "Current Injection in Solids" by Lampert and Mark.
I guess you ment "Space-charge limited conduction with traps in poly(phenylene vinylene) light emitting diodes" from Volume 82. Sadly I have no access to this paper ( I don't know why, because my university has the license for APL)
