Electronic structure of InAs and InSb surfaces: density functional theory and angle-resolved photoemission spectroscopy

Abstract

The electronic structure of surfaces plays a key role in the properties of quantum devices. However, surfaces are also the most challenging to simulate and engineer. Here, we study the electronic structure of InAs(001), InAs(111), and InSb(110) surfaces using a combination of density functional theory (DFT) and angle-resolved photoemission spectroscopy (ARPES). We were able to perform large-scale first principles simulations and capture effects of different surface reconstructions by using DFT calculations with a machine-learned Hubbard U correction [npj Comput. Mater. 6, 180 (2020)]. To facilitate direct comparison with ARPES results, we implemented a "bulk unfolding" scheme by projecting the calculated band structure of a supercell surface slab model onto the bulk primitive cell. For all three surfaces, we find a good agreement between DFT calculations and ARPES. For InAs(001), the simulations clarify the effect of the surface reconstruction. Different reconstructions are found to produce distinctive surface states. For InAs(111) and InSb(110), the simulations help elucidate the effect of oxidation. Owing to larger charge transfer from As to O than from Sb to O, oxidation of InAs(111) leads to significant band bending and produces an electron pocket, whereas oxidation of InSb(110) does not. Our combined theoretical and experimental results may inform the design of quantum devices based on InAs and InSb semiconductors, e.g., topological qubits utilizing the Majorana zero modes. I. INTRODUCTIONThe narrow-gap III-V semiconductors InAs and InSb (InX) have attractive material parameters, including small effective mass, large Lande g-factor, and large spin-

Best practices for first-principles simulations of epitaxial inorganic interfaces

“…DFT+U(BO) has been demonstrated to achieve comparable accuracy to a hybrid functional at the computational cost of a semi-local functional for transition metal monoxides, europium chalcogenides, and narrow-gap semiconductors. It has enabled conducting unprecedented simulations of large surface and interface models, involving materials such as InAs, InSb, GaSb, HgTe, and EuS, which are not properly described by semi-local functionals [54,190,192].…”

Structure prediction of epitaxial inorganic interfaces by lattice and surface matching with Ogre

“…Owing to quantum size effects, a large number of layers of each material must be included in the interface model to converge its properties. 19,57,58 Moreover, domain matched interfaces may require large supercells. This often amounts to models containing hundreds of atoms.…”

Dependence of the electronic structure of the EuS/InAs interface on the bonding configuration

“…The U ef f values obtained therein were U In,p ef f = -0.5 eV, U As,p ef f = -7.5 eV, and U Eu,f ef f = 8.4 eV. The PBE+U(BO) method with these parameters has been used successfully for InAs surfaces [54] and the InAs/GaSb interface [55]. A plane-wave basis set was used with a kinetic energy cutoff of 450 eV.…”

“…The convergence criterion used in the structural relaxation was for the Hellman-Feynman forces acting on ions to be below 0.01 eV/ Å. Bulk band unfolding [54] was applied to all band structures to project the slab band structure onto the primitive cell and facilitate comparison with ARPES experiments. The spin-polarized density of states (DOS) of calculations with SOC was plotted by extracting the DOS of the majority spin channels and minority spin channels along the easy axis.…”

“…Recently, we have developed a method of machine learning the optimal value of the effective Hubbard U parameter by Bayesian optimization (BO) [46]. The PBE+U(BO) method has been demonstrated to provide a reliable description of bulk EuS and InAs [46], as well as InAs surfaces [54] and interfaces [55]. Here, we use PBE+U(BO) to study the electronic structure of the EuS/InAs (001) interface.…”