Band Alignments of Ternary Wurtzite and Zincblende III-Nitrides Investigated by Hybrid Density Functional Theory

Abstract

Band gaps and electron affinities of binary and ternary, wurtzite (wz-) and zincblende (zb-) III-nitrides are investigated using a unified hybrid density functional theory, and band offsets between wz- and zb- alloys are calculated using Anderson’s electron affinity model. A conduction (and valence) band offset of 1.85 (0.89) eV has been calculated for zb-GaN/InN heterojunctions, which is 0.25 eV larger (and 0.26 eV smaller) than that of the wz- counterpart. Such polarization-free zb-GaN/InGaN/GaN quantum well structures with large conduction band offsets have the potential to suppress electron leakage current and quantum-confined Stark effects (QCSEs). Contrarily, the conduction (and valence) band offset of zb-AlN/GaN heterojunctions is calculated to be 1.32 (0.43) eV, which is 1.15 eV smaller (and 0.13 eV larger) than that of the wz- case. The significant reduction in zb-AlN/GaN band offsets is ascribed to the smaller and indirect band gap of zb-AlNthe direct-to-indirect crossover point in zb-Al X Ga1–X N is when X ∼ 65%. The small band gap of the zb-AlN barrier and the small conduction band offsets imply that electrons can be injected into zb-AlN/GaN/AlN quantum well heterostructures with small bias and less energy loss when captured by the quantum wells, respectively, i.e., loss as heat is reduced. The band gap of ternary III-nitrides does not linearly depend on alloy compositions, implying a nonlinear dependence of band offsets on compositions. As a result, the large bowing of the conduction band offset is identified and ascribed to the cation-like behavior of the conduction band minimum, while the linear dependence of the valence band offset on compositions is attributed to the anion-like character of the valence band maximum.

Thermal conductivity of AlXGa1-XN and β-Ga2O3 semiconductors

“…The electronic band structure of the Al x Ga 1−x N alloys is changed with the Al composition. The bandgap dependence on the composition is almost linear between the values of the binaries -3.4 eV (GaN) and 6.0 eV (AlN) [66]. However, at x = 0.09, the order of the valence bands is changed from Γ 9 , Γ 7+ , Γ 7− to Γ 7 +, Γ 9 Γ 7− [67] which has a significant effect on the emission polarization in deep ultraviolet light-emitting diodes (DUV-LEDs).…”

Bayesian Optimization of Hubbard U’s for Investigating InGaN Superlattices

“…Sun and co-workers [15] estimated a band gap of 1.64 eV based on the bowing parameters from literature. Tsai and Bayram [51] reported a KS gap of 1.57 eV for the ternary wurtzite-based nitride In 0.5 Ga 0.5 N, which has the same chemical composition as the (1:1) SL. Again, the best match to HSE06 (1.46 eV) among the considered XC functionals is achieved while using the optimized U-values obtained in this work.…”

Origins of the Schottky Barrier to a 2DHG in a Au/Ni/GaN/AlGaN/GaN Heterostructure

“…19 Our device (Supporting Information A), highlighted in Figure 1(a), includes a current path consisting of a maximum SB of 1.65 eV (Figure 1 11 and Chen et al, who reported 56 kΩ/sq for 12 nm AlGaN. 12 Using p-InGaN is a major contributor to the reduction of the contact resistivity because the conduction band offset between GaN and InN is 1.6 eV, 20 leading to an electron affinity of InN of 5.91 eV, higher than any metal work-function. The ternary compound of p-GaN and InN has an estimated valence band offset of 1.15 eV 20 that should reduce the resistance between metal and 2DHG significantly.…”

“… 12 Using p-InGaN is a major contributor to the reduction of the contact resistivity because the conduction band offset between GaN and InN is 1.6 eV, 20 leading to an electron affinity of InN of 5.91 eV, higher than any metal work-function. The ternary compound of p-GaN and InN has an estimated valence band offset of 1.15 eV 20 that should reduce the resistance between metal and 2DHG significantly. The values of resistivity obtained in this study vary from ρ c ≈ 5.6 × 10 –4 Ω cm 2 (16 nm) to ρ c ≈ 5.1 × 10 –4 Ω cm 2 (30 nm) and show a relative independence to thickness of u-GaN, in Figure 2 (c), contrary to the reported trend from the figure in the abstract.…”