Theoretical analysis of disorder effects on electronic and optical properties of the quaternary alloy In_1–xGa_xAs_ySb_1–y epilayer on GaSb and InAs

Abstract

The effects of structural and chemical disorder on electronic and optical properties of In 1−x Ga x As y Sb 1−y quaternary alloy are studied on the basis of a modified virtual crystal approximation calculated within a simple tight-binding sp 3 s* theory, which incorporates relaxation parameters and compositional disorder as an effective potential. Using a minimal set of fitting parameters, we show that such an approach provides analytical results for calculating energy gaps and bowing parameters. The electronic structure are studied for In 1−x Ga x As y Sb 1−y (x = 0.5, y = 0.5) and In 1−x Ga x As y Sb 1−y lattice matched to GaSb and as well as to InAs. In addition, a method for calculating the refractive indices at energies below the direct band gap edge is presented. The photon energy dependence of the refractive index is calculated with the model of dielectric constants of semiconductors based on simplified models of the interband transitions. Also the composition dependence of the refractive index is discussed; the result indicates that the refractive index increases with alloying for an In 1−x Ga x As y Sb 1−y lattice matched to InAs and GaSb. The lattice thermal resistivity has been calculated using interpolation schemes. The result indicates that the thermal resistivity of an In 1−x Ga x As y Sb 1−y lattice matched to InAs and GaSb for the composition of ( 0 1 x ≤ ≤ ) increases markedly with alloying and exhibits a maximum value of about 41 W −1 deg cm at an alloying composition of x ≅ 0.45 and about 40 W −1 deg cm at an alloying composition of x ≅ 0.50 for InGaAsSb on a substrate of GaSb and InAs, respectively.

Modelling of bandgap and band offset properties in III-N related heterostructures

“…The common practice is to employ the so-called virtual crystal approximation (VCA) to the tight binding Hamiltonian matrix elements and bond length with and without the compositional disorder of the alloy semiconductor. Detailed treatment requires the inclusion of the compositional disorder effect on the electronic properties [19,20]. In the case of a ternary semiconductor alloy we assume a nonlinear composition dependence for the bond length, expressed as [20] …”

“…Detailed treatment requires the inclusion of the compositional disorder effect on the electronic properties [19,20]. In the case of a ternary semiconductor alloy we assume a nonlinear composition dependence for the bond length, expressed as [20] …”

Tight binding modeling of electronic properties of III‐V based heterostructures

“…(2), δ c is the difference between the dimensionless relaxation parameters ξ AC :B and ξ BC :A [23,24] …”

Tight binding modelling of electronic band structure in conventional InGaN/GaN and dilute GaAsN/GaAs nitride heterostructures

“…is the undistorted part of bond length, obtained using the virtual crystal approximation and [7,8] : :…”