Effect of a skin-deep surface zone on the formation of a two-dimensional electron gas at a semiconductor surface

Abstract

Two-dimensional electron gases (2DEGs) at surfaces and interfaces of semiconductors are described straightforwardly with a one-dimensional (1D) self-consistent Poisson-Schrödinger scheme. However, their band energies have not been modeled correctly in this way. Using angle-resolved photoelectron spectroscopy we study the band structures of 2DEGs formed at sulfur-passivated surfaces of InAs(001) as a model system. Electronic properties of these surfaces are tuned by changing the S coverage, while keeping a high-quality interface, free of defects and with a constant doping density. In contrast to earlier studies we show that the Poisson-Schrödinger scheme predicts the 2DEG band energies correctly but it is indispensable to take into account the existence of the physical surface. The surface substantially influences the band energies beyond simple electrostatics, by setting nontrivial boundary conditions for 2DEG wave functions.

Engineering Carrier Effective Masses in Ultrathin Quantum Wells of IrO2

“…Our measurements for IrO 2 lie in striking contrast to nearly all other quantum well systems investigated to date, such as Ag/Cu(111) [5], Au/Ag(111) [4], GaAs/AlGaAs [1,2], InAs (001) [3], and SrTiO 3 (001) [26,27], for which the effective mass is weakly dependent (changes of order ∼ 10%) on sub-band index or . The color coding by sub-band index is the same as used in Fig.…”

“…In the simplest picture, confinement in the out-of-plane direction results in quantized, two-dimensional sub-bands. In nearly all so-called "quantum well" systems investigated to date (e.g., semiconductor quantum wells [1][2][3] and noble metals [3][4][5][6]), the in-plane effective mass is, at most, only weakly dependent on the sub-band index. The ability to deterministically engineer the effective mass or density of states of each sub-bands could have implications for technological applications which depend on quantum confinement, such as quantum cascade lasers [7], tunnel diodes [8], and photocatalysts [9].…”

On the origin of electron accumulation layer at clean InAs(111) surfaces

“…The experimental results unambiguously suggest that the band structure of occupied conduction band states in the vicinity of the Γ-point can be well fit with a parabola. The result of our numerical simulations is in agreement with the previously reported experimental value 73,74 . It worth noting that a curvature of the conduction band in the vicinity of the Γ-point can be assessed 75 using e.g.…”

“…Interestingly, the electronic structure of a supercell still enjoys the bandgap of 0.5 eV at the Γ-point of the Brillouin zone. The curvature of the in-plane dispersion of unoccupied states was discussed in many experimental works 31,73,74 . Typically, one relies on ARPES technique which probes E(k ) for occupied states directly.…”

Dirac energy spectrum and inverted bandgap in metamorphic InAsSb/InSb superlattices

“…The Fermi energy extracted from the low temperature ARPES data is ~150 meV, roughly 4 times higher than that obtained from the bulk Hall measurements 20 . The most likely reason for this is the presence of a surface accumulation layer [21][22][23] . The Fermi energy value is in reasonable agreement with estimates based on knowledge of the position of the Fermi-stabilization level and the bending of the conduction band edge energy near the surface.…”