Topologically trivial zero-bias conductance peak in semiconductor Majorana wires from boundary effects

We show that a topologically trivial zero-bias conductance peak is produced in semiconductor-superconductor hybrid structures due to a suppressed superconducting pair potential and/or an excess Zeeman field at the ends of the heterostructure, both of which can occur in experiments. The zero-bias peak (ZBP) (a) appears above a threshold parallel bulk Zeeman field, (b) is stable for a range of bulk field before splitting, (c) disappears with rotation of the bulk Zeeman field, and (d) is robust to weak disorder fluctuations. The topologically trivial ZBPs are also expected to produce splitting oscillations with the applied field similar to those from Majorana fermions. Because of such strong similarity with the phenomenology expected from Majorana fermions, we find that the only unambiguous way to distinguish these trivial ZBPs (of height 4e(2)/h) from those arising from Majorana fermions (of height 2e(2)/h) is by comparing the (zero-temperature) peak height and/or through an interference experiment.