We present a novel model to describe conduction band of GaNxAs1−x (GaNAs). As well known, GaNAs shows exotic behavior such as large band gap bowing. Although there are various models to describe the conduction band of GaNAs, origin of the band gap bowing is still under debate. On the basis of perturbation theory, we show that the behavior of conduction band is mainly arising from intervalley mi...

DFTB is a recent general purpose implementation of density-functional based tight binding. One of the early motivators to develop this code was to investigate lanthanide impurities in nitride semiconductors, leading to a series of successful studies into structure and electrical properties of these systems. Here we describe our general framework to treat the physical effects needed for these pr...

The optical properties of InGaN/GaN laser diode based on quaternary alloys stopper and superlattice layers are numerically studied using ISE TCAD (Integrated System Engineering) simulation program. Improvements in laser optical performance have been achieved using quaternary alloy as superlattice layers in InGaN/GaN laser diodes. Lower threshold current of 18 mA and higher output power and slop...

An ab initio study of nitride-based heteroepitaxial interfaces that uses norm-conserving pseudopotentials and explicitly treats the strain due to lattice mismatch is presented. Strain effects on the band offsets range from 20% to 40%. The AlN/GaN/InN interfaces ~with AlN in-plane lattice constant! are all of type I, while the Al 0.5Ga0.5N/AlN zinc-blende ~001! interface is of type II. Further, ...

Results of density-functional calculations for isolated transition metal (TM = V, Cr, Mn, Fe, Co, Ni on cation sites) doped GaN demonstrate a novel magnetic metastability in dilute magnetic semiconductors. In addition to the expected high spin ground states (4muB/Mn and 5muB/Fe), there are also metastable low spin states (0muB/Mn and 1muB/Fe)--a phenomenon that can be explained in simple terms ...