Band Offsets from Angle‐Resolved Valence Band Photoemission Spectroscopy

The conduction band offset ϕ0 at semiconductor surfaces and interfaces is a crucial parameter for quantum devices exploiting proximity‐induced collective states such as superconductivity and magnetism. Recently, a method combining angle‐resolved conduction band and core‐level photoelectron spectroscopy was shown to yield band offsets aligning well with direct measurements of quantized conduction subband energies. However, the method was limited to surfaces with native accumulation layers. To address this shortcoming, a broader approach is proposed using angle‐resolved valence band (VB) photoemission spectra, applicable to all semiconductor surfaces and interfaces. The goal is to identify the top of the VB by fitting a summation of contributions from individual layers to the VB signal at the Γ‐point of the Brillouin zone. The technique achieves high accuracy, matching conduction subband‐derived offsets for InAs(111) surfaces, with a deviation of only 51 meV – significantly better than conventional leading‐edge methods. This approach is applied to systems relevant for topological superconductivity, extracting band offsets for InSb(110)/vacuum (ϕ0 = 5 ± 21 meV), oxidized InSb(110) (ϕ0 = 65 ± 69 meV), hydrogen‐cleaned InSb(110) (ϕ0 = 40 ± 63 meV), and InSb(110)/Al interfaces (ϕ0 = 74 ± 13 meV), all of which lack observable accumulation layers by angle‐resolved photoemission spectroscopy.