Can someone please tell me how to choose the suitable vlaue of Compensation factor in Ionised Impurity Scattering and when is it appropriate to use the default value of Compensation factor?

Hi @Himanshu_Sharma. This is a tricky question. Unfortunately, you cannot know what compensation factor to use without either i) experimental defect concentrations or ii) calculating the full first-principles defect calculations and self-consistent Fermi level.

The default compensation factor used in amset should be appropriate for systems in which the Fermi level is not pinned deep in the gap and the degree of charge compensation is low. This is generally the case when the system is dopable through extrinsic dopants or possess shallow intrinsic defects.

One option is to test the sensitivity of your system to the defect concentration, by systematically increasing the compensation factor for a specific doping concentration. That way, you can determine at which defect concentrations IMP scattering becomes dominant.

Best,

Alex

Hi @alex , thanks for replying. I got your point without basic calculation we canâ€™t tell about compensation factor but then how can we say that for an extrinsic doping the factor should be 2(the default value)? For an example if extrinsic doping concentration is X and as you suggested we can use the dafult compensation value so it simply doubles the ionised impurity as default defect charge value is 1. So I just want to know how is this defualt compensation factor value is chosen?

The default is based on anecdotal observations that in many materials there is a degree of charge compensation. You can see this on defect transition level diagrams and from self-consistent Fermi level calculations. There is no formal proof it is just an approximation.