Wurtzite BAIN and BGaN alloys for heterointerface polarization engineering

摘要

The spontaneous polarization (SP) and piezoelectric (PZ) constants of B_xAl_(1-x)N and B_xGa_(1-x)N (0 ≤ x ≤ 1) ternary alloys were calculated with the hexagonal structure as reference. The SP constants show moderate nonlinearity due to the volume deformation and the dipole moment difference between the hexagonal and wurtzite structures. The PZ constants exhibit significant bowing because of the large lattice difference between binary alloys. Furthermore, the PZ constants of B_xAl_(1-x)N and B_xGa_(1-x)N become zero at boron compositions of ~87% and ~74%, respectively, indicating non-piezoelectricity. The large range of SP and PZ constants of B_xAl_(1-x)N (BAIN) and B_xGa_(1-x)N (BGaN) can be beneficial for the compound semiconductor device development. For instance, zero heteroin-terface polarization ∆P can be formed for BAlN and BGaN based heterojunctions with proper B compositions, potentially eliminating the quantum-confined Stark effect for c-plane optical devices and thus removing the need of non-polar layers and substrates. Besides, large heterointerface polarization ∆P is available that is desirable for electronic devices.