Abstract: An effective method is introduced to investigate the strained fields and piezoelectric effect in GaN/AlN quantum dots (QDs) with hexagonal truncated pyramid shape.The strain distribution and charge density were calculated using the finite element method (FEM).It is shown that spontaneous and piezoelectric polarization resulted in the separation of electrons and holes,bringing about a strong built-in electric field in the QD structures.The strain field and piezoelectric potential influence the distribution of charges.The electrons are localized near the top of the QDs,and the holes are localized in the wetting layer just below the pyramid.Furthermore,the piezoelectric potential in the QDs affects the electron levels and band edge shape.

Key words: GaN/AlN quantum dot, strain, spontaneous polarization, piezoelectric polarization