The conductance dependences of the edge channels of silicon nanosandwich structures (SNS) on the vertical gate voltage Vg are studied. The experiments are carried out in such a range of Vg, in which the two-dimensional density of holes p2D is stable that made it possible to avoid the changes of the Fermi level position and thereby to unambiguously identify the Aharonov–Casher oscillations. The effect of a spin field-effect transistor at a high temperature (T = 77 K) is demonstrated, which manifests itself in the form of Aharonov–Casher oscillations of longitudinal conductance depending on Vg, which controls the Bychkov–Rashba spin-orbit interaction. This experiment became possible due to the high degree of spin polarization of holes and the long spin-lattice relaxation time because of the extremely small width of the silicon quantum well and the narrowness of its edge channels, which is ensured by the properties of the negative-U-barriers limiting them effectively decreasing the electron-electron interaction.