Self-consistent tight-binding electronic structure of GaN/AlN pyramidal quantum dots

Vivek Ranjan , Christophe Delerue (1) , Guy Allan (1) , Catherine Priester (1)

1 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520

We have employed a second nearest neighbour sp3 tight-binding scheme to study a pyramidal quantum dot of wurtzite GaN embedded in AlN. The largest QD, we have studied, consists of approximately forty thousand atoms. This corresponds to the actual size reported in the experiments. We have computed strains in the system and our calculation includes the piezoelectric field, in addition to the spontaneous polarization. We have observed a reduction in the band gap of the QD. The band gap is strongly dependent on the height of the dot. The lifetime is found to reduce expenentially as the height (size) of the QD increases. In a photoluminescence experiment the in-built field is screened due to the creation of electron-hole pair. This leads to a small blue shift of the PL peak. We have employed a novel self-consistent tight-binding technique to study the screening effect. The results are in agreement with the experiment.

Domaines: Sciences de l'ingénieur [physics]

Vivek Ranjan, Christophe Delerue, Guy Allan, Catherine Priester. Self-consistent tight-binding electronic structure of GaN/AlN pyramidal quantum dots. American Physical Society March Meeting, 2003, Austin, TX, United States. ⟨hal-00146640⟩