  The realization of a viable semiconductor transistor and information
processing devices based on the electron spin has fueled intense basic research
of three key elements: injection, detection, and manipulation of spins in the
semiconductor channel. The inverse spin Hall effect (iSHE) detection of spins
injected optically in a 2D GaAs and manipulated by a gate-voltage dependent
internal spin-orbit field has recently led to the experimental demonstration of
a spin transistor logic device. The aim of the work presented here is to
demonstrate in one device the iSHE detection combined with an electrical spin
injection and manipulation. We use a 3D GaAs channel for which efficient
electrical spin injection from Fe Schottky contacts has been demonstrated in
previous works. In order to experimentally separate the strong ordinary Hall
effect signal from the iSHE in the semiconductor channel we developed epitaxial
ultrathin-Fe/GaAs contacts allowing for Hanle spin-precession measurements in
applied in-plane magnetic fields. Electrical injection and detection is
combined in our transistor structure with electrically manipulated spin
distribution and spin current which, unlike the previously utilized electrical
manipulations of the spin-orbit field or ballistic spin transit time, is well
suited for the diffusive 3D GaAs spin channel. The magnitudes and external
field dependencies of the measured signals are quantitatively analyzed using
simultaneous spin detection by the non-local spin valve effect and modeled by
solving the drift-diffusion and Hall-cross response equations for the
parameters of the studied microstructure.
