interactions play a crucial role in nano-electronic device performance.
As the accurate calculation of these interactions requires huge
computational resources, reduction of this burden without losing
accuracy poses an important challenge. Here, we investigate the
electron–phonon interactions of nano-devices using two
first-principles-based methods in numerically efficient manners. The
first method is the Lowest Order Approximation (LOA) version of the
computationally burdensome self-consistent Born approximation method.
The LOA method incorporates the effect of each phonon mode on the
electronic current perturbatively. In this work, we theoretically
resolve the discrepancy between two conventional approaches of direct
LOA calculation. To validate the correct approach, we compared its
output with a completely different method (second method) named Special
Thermal Displacement (STD) method. The STD method uses non-interacting
transport calculation of the displaced atomic configuration of a device.
We apply both methods to two thin-film nanodevices: 2D silicon
junctionless FET and n-i-n FET. Both methods justify each other by
providing similar results and exhibiting important quantum phenomena,
such as phonon-assisted subthreshold swing degradation and tunneling.