Comparison of Bowing Behaviors Between III–V and II–VI Common-Cation Semiconductor Ternary Alloys

Abstract

The scope of the present investigation is to make a clear contrast between the bandgap bowing characters of III–V and II–VI compound-semiconductor common-cation ternary alloys. For this aim, both the sp ³ s ^* tight-binding method, with the inclusion of spin–orbit coupling, and the full-potential linear augmented plane-wave technique are used to calculate the partial and total densities of states, the constituent ionicity, and the total electron charge density for the common-cation GaSb _x As_1−x and CdSe _x Te_1−x ternary alloys. The results show that the bowing is sensitive to competition between the anions for trapping/losing electric charges. The lack of this competition would result in complete absence of the bowing, as is the case for common-anion ternary alloys. In the common-cation ternary alloys studied herein, the bowing is found to be proportional to the electronegativity of the anions χ ^anion (i.e., the 6-valency anions are more electronegative than the 5-valency ones, and consequently the former result in stronger intercompetition and yield stronger bowing in the II–VI alloys) and also proportional to the relative mismatch in electronegativity between the competing anions $({\Updelta}\chi^{\rm{anion}}/\chi^{\rm{anion}}_{\rm{ave}}).$ The excellent agreement between our theoretical results and recent photoluminescence data corroborates our claim.