  We present the first findings of the spin transistor effect caused by the
Rashba gate-controlled ring embedded in the p-type self-assembled silicon
quantum well that is prepared on the Si (100) surface. The coherence and phase
sensitivity of the spin-dependent transport of holes are studied by varying the
value of the external magnetic field and the gate voltage that are
perpendicular to the plane of the double-slit ring. Firstly, the quantum
scatterers connected to two one-dimensional leads and the quantum point contact
inserted in the one of the arms of the double-slit ring are shown to define the
amplitude and the phase of the Aharonov-Bohm and the Aharonov-Casher
conductance oscillations. Secondly, the amplitude and phase sensitivity of the
0.7 feature of the hole quantum conductance staircase revealed by the quantum
point contact inserted are found to result from the interplay of the
spontaneous spin polarization and the Rashba spin-orbit interaction.
