Pseudo-potential calculations of the electronic and optical properties of GaxAlyIn1–x–yAs
A method for calculating the electronic structure of the quaternary alloy GaAlInAs is presented with zinc blende structure. We have used the empirical pseudo-potential method coupled with the virtual crystal approximation (VCA). The electronic structures are studied for GaAlInAs (x = 0.24, y = 0.24) and GaAlInAs lattice matched to InP as well GaAs. In addition a method for calculating the refractive index is presented, which we used the Sellmeir model. The composition dependence of the refractive index is discussed, the results indicate that refractive index decrease with alloying composition of the quaternary alloy GaAlInAs lattice matched to InP and GaAs.
Design optimization of InGaAsP-InGaAlAs 1.55 /spl mu/m strain-compensated MQW lasers for direct modulation applications
A comprehensive simulation study of InGaAsP (well)/InGaAlAs(barrier) 1.55 /spl mu/m strain-compensated MQW lasers is presented. For MQWs, a uniform vertical distribution of holes is achieved due to a reduced effective hole confinement energy by optimizing the bandgap and strain of the barriers and p-doping in the active region. Some preliminary results are also presented for the manufactured lasers using these QWs indicating a good material platform.
Band Gaps of Semiconductor Alloys
It is shown, on the basis of perturbation theory and a simple assumption about the matrix elements of the random scattering potential, that the effect of alloy disorder is inevitably to reduce the band gap of a semiconductor alloy below its virtual-crystal value. The conclusion, which was previously suggested by Van Vechten and Bergstresser (VB) on the basis of a more intuitive argument, is in agreement with existing theory and calculation. In contrast to VB, however, the present treatment predicts that the magnitude of the disorder-induced shift will vary from one direct gap to another in the same alloy, and that the uppermost gaps may be larger than a straight-line interpolation of the gaps of the constituents. This prediction appears to be corroborated by the electroreflectance studies of Thompson et al. on $\mathrm{Ga}({\mathrm{As}}_{x}{\mathrm{P}}_{1\ensuremath{-}x})$.