The authors report, for the first time, a novel SiGe/Si n‐type hetero nanotube (HNT) junctionless field‐effect transistor (JLFET), which leads to a remarkably enhanced performance below the sub‐10 nm gate length. It is shown that valence band discontinuity in the HNT JLFET causes tunnelling width of the channel–drain interface to increase and therefore diminishes the lateral tunnelling of electrons in the OFF state. The impact of high‐κ spacers and core gate diameter on the dynamic performance of HNT JLFET has also been studied. They show that the inclusion of high‐κ spacers does not affect the dynamic performance of the HNT JLFET. It is demonstrated using calibrated 2D simulations that the proposed device exhibits a smaller value of DIBL 4 mV/V, sub‐threshold slope almost 60 mV/decade, and an improved I_ON/I_OFF ratio of ∼10¹² even for sub‐10 nm gate lengths.