Direct Observation of Two-Dimensional Electron Gas with Low Effective Mass in Atomically Thin InTe

Atomically thin InTe, a III-VI analogue of InSe, has recently emerged as a promising two-dimensional semiconductor for nanoelectronics, yet the nature of its two-dimensional electron gas (2DEG) has remained experimentally elusive. Here, using scanning tunneling microscopy (STM) combined with quasiparticle interference (QPI) imaging, we present direct evidence of the existence of a 2DEG in monolayer and bilayer InTe. Bias-dependent standing-wave patterns reveal a parabolic conduction-band dispersion in both thicknesses. Quantitative analysis yields a low electron effective mass of 0.241m_e in monolayer InTe, smaller than that of monolayer InSe/BLG (∼0.27m_e). In bilayer InTe, interlayer coupling lifts the conduction-band-edge degeneracy, and produces two subbands with effective masses of 0.197m_e and 0.802m_e. Density functional theory calculations are in good agreement with the experimental observations. These results establish atomically thin InTe as a promising platform for low-dimensional electronic physics and nanoelectronic applications.