  Spin transport property of polarization induced two-dimensional electron gas
channel formed in the central vertical plane of a wedge-shaped
\textit{c}-oriented GaN nanowall is investigated theoretically. Since the
confining potential preserves the spatial symmetry between the conduction and
valence band, the Rashba effect is suppressed in this system even when the
shape of the wedge is asymmetric. It has been found that the relaxation of the
electron spin oriented along the direction of the confinement via
D'yakonov-Perel' (DP) mechanism, which is the dominant process of relaxation in
this high mobility channel, is entirely switched off at low temperatures. Spin
relaxation can be turned on by applying a suitable bias at the gate. Exploiting
this remarkable effect, a novel all electrically driven spin-transistor has
been proposed.
