Further improvement of the power conversion efficiencies of conventional perovskite ferroelectric oxides has been strongly impeded by their wide band gaps. Here, we use several band gap engineering strategies to design low band gap ferroelectric materials from first principles. We show that polarization rotation is useful for reducing the band gaps of strongly distorted perovskites. A variety o...

Discussion of band gap behavior based on first principles calculations of electronic band structures for various short period nitride superlattices is presented. Binary superlattices, as InN/GaN and GaN/AlN as well as superlattices containing alloys, as InGaN/GaN, GaN/AlGaN, and GaN/InAlN are considered. Taking into account different crystallographic directions of growth (polar, semipolar and n...

A periodic arrangement of atoms in a crystal presents a periodic potential for electrons. The bragg diffraction of electrons from the atoms may lead to a band gap, which represents a range of frequencies the electrons cannot have in the crystal. An analogous effect takes place in photonic crystals, which are periodic arrangement of layers of dielectric media. Scattering at the interface of the ...

We present a growth process relying on pulsed laser deposition for the elaboration of complex van der Waals heterostructures large scales, at 400 °C CMOS-compatible temperature. Illustratively, we define multilayer quantum well geometry through successive in situ growths, leading to WSe2 being encapsulated into WS2 layers. The structural constitution is confirmed by Raman spectroscopy combined ...