  We calculate the linear conductance of a two-dimensional electron gas
(2DEG)-based junction between a normal semiconductor section and a hybrid
semiconductor-superconductor section, under perpendicular magnetic field. We
consider two important terms often neglected in the literature, the
magneto-orbital and transverse Rashba spin-orbit. The strong orbital effect due
to the magnetic field yields topological phase transitions to nontrivial phases
hosting Majorana modes in the hybrid section. The presence of a potential
barrier at the junction interface reveals the Majorana phases as quantized
plateaus of high conductance, for low values of the chemical potential. In wide
junctions (or large chemical potentials) the phase transitions occur at low
magnetic fields but the magneto-conductance becomes anomalous and lacks clearly
quantized plateaus.
