Band Alignment at Ga_xIn_1–xP/Al_yIn_1–yP Alloy Interfaces from Hybrid Density Functional Theory Calculations

Abstract

The composition dependence of the natural band alignment at the GaxIn1–xP/AlyIn1–yP alloy interface is investigated via hybrid functional based density functional theory. The direct–indirect crossover for the GaxIn1–xP and AlyIn1–yP alloys is calculated to occur for x = 0.9 and y = 0.43. The calculated GaxIn1–xP/AlyIn1–yP interface band alignment shows a crossover from type‐I to type‐II with increasing Ga content x. The valence band offset is essentially positive irrespective of the alloy compositions, and amounts up to 0.56 eV. The conduction band offset varies between −0.85 and 1.16 eV.

GaInP/AlInP(001) Interfaces from Density Functional Theory

“…In the latter, the fraction of exact exchange is increased to for a better match with the measured bandgaps. [ 7 ] The resulting changes in the bulk bandgaps with respect to the default mixing of 25% are small, however, compared with the conduction band offsets calculated in this work. Therefore, the choice of the mixing parameter will not affect the conclusions of the present study.…”

“…[ 25 ] The direct–indirect bandgap crossover of Ga x In 1− x P and Al y In 1− y P occurs for In‐poor and In‐rich stoichiometries, respectively. [ 7,26–28 ] The measured bandgaps of randomly ordering Ga 0.5 In 0.5 P and Al 0.5 In 0.5 P alloys amount to about 1.9 [ 29,30 ] and 2.3 eV. [ 31 ] In Figure 1 , we show the band structures of CuPt‐type ordered GaInP and AlInP crystals, calculated at the respective equilibrium lattice constants of 5.71 and 5.70 Å obtained from structural relaxation.…”

“…The full exploitation of this flexibility profits from detailed knowledge of the electronic properties of III–V compounds and their alloys, [ 2 ] surfaces, [ 3 ] and interfaces. [ 4–7 ]…”

“…[ 8 ] The branch‐point energy method [ 9–15 ] has recently been used to address the natural band alignment at this interface. [ 7 ] Assuming random ordering in the Ga 0.5 In 0.5 P and Al 0.5 In 0.5 P alloys, valence and conduction band offsets of 0.18 and −0.49 eV, respectively, was calculated. [ 7 ] These values, however, do not account for the influence of strain, surface orientation and interface bonding.…”

“…[ 7 ] Assuming random ordering in the Ga 0.5 In 0.5 P and Al 0.5 In 0.5 P alloys, valence and conduction band offsets of 0.18 and −0.49 eV, respectively, was calculated. [ 7 ] These values, however, do not account for the influence of strain, surface orientation and interface bonding. These effects are investigated in the present study, focusing on CuPt‐type ordered crystals, i.e., bulk material with alternating group III layers perpendicular to the or direction, as formed spontaneously in metal–organic vapor phase epitaxy epilayers.…”