Materials currently used for detection in the infrared spectral region have notoriously poor structural properties. In search of a better narrow‐gap material, we have addressed the structural properties of bismuth‐bearing III‐V semiconductor alloys theoretically. Because the Bi compounds are not known to form zinc‐blende structures, only the anion‐substituted alloys InPBi, InAsBi, and InSbBi are considered candidates as narrow‐gap semiconductors. We calculate the bond energies and lengths for the zinc‐blende Bi compounds and their diluted and concentrated alloys. Strain coefficients for the compounds are calculated, and predictions for the mixing enthalpies, miscibility gaps, and critical temperatures are made. Miscibility calculations indicate that InSbBi will be the most miscible, and because of the large lattice mismatch of the constituents, InPBi will be the most difficult to mix. Tendencies toward cluster formation and deviations from randomness in the alloys are considered. Calculations of the hardn...

Structural properties of bismuth-bearing semiconductor alloys

Abstract Here we present evidence that the gap between the highest occupied and lowest unoccupied molecular orbitals (HOMO–LUMO gap) can be tuned (1.12–1.89 eV) by changing the Ga composition of Bi 3 Ga y anionic and neutral clusters, some of which display special stability. Collaboratively, mass spectrometry, photoelectron spectroscopy and computational results show that Bi 3 Ga 2 - is a very stable cluster with a large calculated HOMO–LUMO gap of 1.89 eV, and can be viewed as a gas phase Zintl analogue of Sn 5 2 - , already synthesized in the solution phase. The stability of Bi 3 Ga 2 - is further attributed to the fact that it has 12 valence electrons and possesses a closo structure in agreement with Wade’s rules.

http://absimage.aps.org/image/MAR09/MWS_MAR09-2008-002405.pdf

Electronic Structure of Bi$_{3}$Ga$_{y}^-$ Semiconductor Clusters and the Special Stability of Bi$_{3}$Ga$_{2}^{-}$ - A Gas Phase Zintl Analogue

As an effective means to adjust the properties of 2D materials, type‐II van der Waals (vdW) heterostructures have been under extensive research due to their significantly reduced carrier recombination probability and extended carrier lifetime. Herein, stable vdW heterostructures based on arsenic phosphorus (AsP) and transition metal dichalcogenides are designed. The geometry, electronic, and optical properties for type‐II AsP/MX2 heterostructures (M = Mo, W; X = S, Se) by first‐principle calculations are systematically explored and their application in solar cell materials is predicted. AsP/MX2 heterostructures are indirect semiconductors with the quasiparticle bandgap ranging from 1.49 to 2.02 eV. They effectively widen the light absorption of AsP monolayers in visible and ultraviolet regions. It is worth noting that AsP/WSe2 heterostructure can form a built‐in electric field (0.832 eV Å−1) and have a minor exciton binding energy (0.22 eV), suggesting that it is a potential solar cell material. The power conversion efficiency is more than 15%. The results will provide a theoretical basis for sustainable energy applications of AsP‐based vdW heterostructures in the future.

Type‐II van der Waals Heterostructures Based on AsP and Transition Metal Dichalcogenides: Great Promise for Applications in Solar Cell

Low-dimensional systems have strong multi-body interactions and fewer geometric constraints due to the screening effect of the Coulomb interaction. We use the single-shot GW-Bethe Salpeter equation (G0W0-BSE) to calculate the electronic and optical properties of six-blue arsenic phosphorus (β-AsP) conformers. The results show significant anisotropic exciton effects of covering visible regions, which apparently changed the light absorption. The maximum exciton binding energy is up to 0.99 eV, which is more extensive than the black phosphorus monolayer (0.9 eV). We predict that the different orbital contributions to valence bands may cause the anisotropic exciton effect difference. Our results indicate that β-AsP monolayers with the large binding energies of exciton hold a great promise for applications in optoelectronic devices.

Quasiparticle energies and significant exciton effects of monolayered blue arsenic phosphorus conformers.

for large size- and chemical-mismatched isovalent semiconductor alloys, such as n and bi substitution on as sites in gaas, isovalent defect levels or defect bands are introduced. the evolution of the defect states as a function of the alloy concentration is usually described by the popular phenomenological band anticrossing (bac) model. using first-principles band-structure calculations we show that at the impurity limit the n-(bi)-induced impurity level is above (below) the conduction- (valence-) band edge of gaas. these trends reverse at high concentration, i.e., the conduction-band edge of gaas1-xnx becomes an n-derived state and the valence-band edge of gaas1-xbix becomes a bi-derived state, as expected from their band characters. we show that this band crossing phenomenon cannot be described by the popular bac model but can be naturally explained by a simple band broadening picture.

http://absimage.aps.org/image/MAR12/MWS_MAR12-2011-008127.pdf

Band crossing in isovalent semiconductor alloys with large size mismatch

Chemical modification can effectively control the quantum spin Hall (QSH) state by changing the lattice constant or topological phase transition. We functionalized ultraflat stanene with hydrogen and halogens on a single side (s-SnX) and both sides (b-SnX). It was found that the buckled heights of the neighboring Sn atoms for s-SnX were still zero, while b-SnX changed into a buckled structure, which is consistent with previous studies. In this work, the electronic and topological properties of s-SnX (X = H, F, Cl, Br, I) were mainly studied based on first-principles calculations. We predicted that s-SnF, s-SnCl and s-SnBr would be topological insulators (TIs). It was found that the band structures of s-SnF, s-SnCl, s-SnBr have s-p band inversions and semimetal-to-semiconductor transitions considering spin orbit coupling (SOC) with the largest band gap of 0.25 eV. The edge bands of calculating the edge states cross linearly, and the numbers of edge bands passing through the zero energy level between –X and Γ point are odd, indicating that s-SnF, s-SnCl and s-SnBr are TIs. Ultraflat stanene functionalized by hydrogen and halogen atoms can effectively control QSH states. It is proved that functionalization provides more choices for topological insulator materials and topological device applications.

Electronic and Topological Properties of Ultraflat Stanene Functionalized by Hydrogen and Halogen Atoms

In this chapter, electronic properties of dilute bismide III-V semiconductors are reviewed briefly. Theoretical and computational methods are collected and discussed extensively. Empirical models, including tight-binding (TB) model, band anti-crossing (BAC), valance band anti-crossing (VBAC), and k·p model, have been widely applied in calculations of electronic properties of dilute bismide III-V materials. First-principle methods have also been used to investigate many kinds of Bi-containing compounds, such as models of bulk, surface, and nanostructure. Several combined methods are also reviewed.

Huiyan Zhao

Papers

Quasiparticle energies and significant exciton effects of monolayered blue arsenic phosphorus conformers.

Electronic and Topological Properties of Ultraflat Stanene Functionalized by Hydrogen and Halogen Atoms

Electronic Properties of Dilute Bismides