p-type doping of GaInNAs quaternary alloys

a r t i c l e i n f o a b s t r a c t Using the first-principles band-structure method, we investigate the p-type doping properties and band structural parameters of the random Ga 1−x In x N 1− y As y quaternary alloys. We show that the Mg Ga substitution is a better choice than Zn Ga to realize the p-type doping because of the lower transition energy level and lower formation energy. The natural valence band alignment of GaAs and GaInNAs alloys is also calculated, and we find that the valence band maximum becomes higher with the increasing In composition. Therefore, we can tailor the band offset as desired which is helpful to confine the electrons effectively in optoelectronic devices. The band gaps and lattice constants of conventional III–V alloys A 1−x B x C can be individually tuned by changing the composition x. The band gap can be described as E g (x) = (1 − x)E g (AC) + xE g (BC) − bx(1 − x), (1) where b is the bowing parameter and is composition independent. GaAs 1−x N x and Ga 1−x In x N 1− y As y alloys have simulated great interests because of their unique reduction of band gap and giant composition dependent bowing parameter [1–5]. Wei et al. suggested that the band gap variation as a function of x in GaAs 1−x N x can be divided into two parts: (i) a bandlike part where the bowing coefficient is relatively small and nearly constant; (ii) an impurity like one where the bowing coefficient is considerably large and composition dependent. These results reflect the large differences between N and As in the atomic orbital energies and sizes [2]. The band anti-crossing model has also been proposed to explain the band gap reduction for GaInNAs alloys, which is consistent with the experimental results [3]. The Ga 1−x In x N 1− y As y alloys have the great potential applications for long-wavelength (1.3–1.88 μm) optoelectronic devices, which have been studied extensively [6–8]. The quaternary alloys have been successfully synthesized by incorporating nitrogen to GaInAs alloys. However, the increase of nitrogen will lead to poor crystal quality due to the lattice constant mismatch. As a result, the more indium composition is requested, which can also reduces the band gap and tensile strains [7]. The 1.3 μm GaInNAs/GaAs quantum wells …