02. Polarization in GaN/AlN heterostructures

First principles calculation of polarization induced interfacial charges in GaN/AlN heterostructures.
R. Mishra, O. D. Restrepo, S. Rajan, W. Windl, Appl. Phys. Lett. 98, 232114 (2011).

We propose a method to calculate polarization induced interfacial charges in semiconductor heterostructures using classical electrostatics applied to real-space band diagrams from first principles calculations and apply it to GaN/AlN heterostructures with ultrathin AlN layers (4–6 monolayers). We show that the calculated electric fields and interfacial charges are independent of the exchange-correlation functionals used (local density approximation and hybrid). We also find the calculated interfacial charge of (6.8±0.4)×10¹³ cm⁻² to be in excellent agreement with experiments and the value of 6.58×10¹³ cm⁻² calculated from bulk polarization constants, validating the use of bulk constants even for very thin films.