Impact Factor:0.0
DOI number:10.1088/1367-2630/16/11/113065
Journal:New J. Phys.
Key Words:valence band inversion, spin–orbit coupling, electronic structure, optical property, first-principles calculation
Abstract:The problem of achieving high light extraction efficiency in Al-rich AlxGa$_{1-x}$N is of paramount importance for the realization of AlGaN-based deep ultraviolet (DUV) optoelectronic devices. To solve this problem, we investigate the microscopic mechanism of valence band inversion and light polarization, a crucial factor for enhancing light extraction efficiency, in Al-rich AlxGa$_{1-x}$N alloy using the Heyd–Scuseria–Ernzerhof hybrid functional, local-density approximation with 1/2 occupation, and the Perdew–Burke–Ernzerhof functional, in which the spin–orbit coupling effect is included. We find that the microscopic Ga-atom distribution can effectively modulate the valence band structure of Al-rich AlxGa$_{1-x}$N. Moreover, we prove that the valence band arrangement in the decreasing order of heavy hole, light hole, and crystal-field split-off hole can be realized by using nanoscale (AlN)m/(GaN)n (m>n) superlattice (SL) substituting for Al-rich AlxGa$_{1-x}$N disorder alloy as the active layer of optoelectronic devices due to the ultra-thin GaN layer modulation. The valence band maximum, i.e., the heavy hole band, has px- and py-like characteristics and is highly localized in the SL structure, which leads to the desired transverse electric (TE) polarized (E⊥c) light emission with improved light extraction efficiency in the DUV spectral region. Some important band-structure parameters and electron/hole effective masses are also given. The physical origin for the valence band inversion and TE polarization in (AlN)m/(GaN)n SL is analyzed in depth.
Indexed by:Journal paper
Discipline:Natural Science
First-Level Discipline:Physics
Volume:16
Page Number:113065
Translation or Not:no
Date of Publication:2014-11-26