In most of the literature, it is observed that ideality factor decays with increase in temperature. But in few articles, it increases with temperature. Even in one article, I have seen it to vary in triangular shape with increase in temperature but they did not mention the reason. So is there any general law, which can be used to explain all these type of variations?
Dear Bijit
Ideal factor decreases with increase in temperature mathematically according to the following practical relation LnI/V=q/(n_i K_B T)+LnI_° , and this use to find n_i (ideal factor) from the slope, this mean after less steps n_i=(1/0.025)*(1/slope), where 0.025 V=V_th (thermal voltage) , here T at room temperature, and we can rewrite the equation as n_i=(q/K_BT)*(1/slope), therefore the idea factor reciprocal proportional with the temperature. Also, this calculations from dark current, therefore the ideal factor represented property of diode. With my best wishes
Hello Bijit
I think ideal factor give you information about your device, this can help you to analysis your results such as I-V or C-V characterizes. for example if your ideal factor not agreement with the standard values, then there are some problems in your junction such as pinholes may be founded, and you can know from SEM or C-V characterization or from EDS (compositional ), ..etc. Finally ideal factor represent internal efficiency for device.
With my best wishes
My impression is that an ideality factor value rather often results from a fitting procedure where it is not clear what kind of "leftover effects" -- not properly taken into account by the other fitting parameters -- end up in the ideality factor, therefore the physics behind an ideality factor value can be doubtful. Then, an observed temperature dependence of the ideality factor might just result from the temperature dependence of a different quantity, having a different physical origin than the true ideality factor.
Remember that fitting models are just models. They typically suit the given experimental situation more or less well, but never perfectly. To explicitly name an example: It was observed that a possible injection-level dependence of the bulk lifetime of a silicon solar cell might be taken into account by using an ideality factor slightly larger than one -- see Rißland and Breitenstein, SOLMAT 2013 (https://www.researchgate.net/publication/257375410).
Article Evaluation of luminescence images of solar cells for injecti...
At least for silicon solar cells the ideality factor is determined by the dominating recombination mechanism. If this doesn't change with temperature, then the ideality factor should also not change.
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