Study of SnO/ɛ-Ga2O3 p–n diodes in planar geometry

SnO/ε-Ga2O3 vertical p–n diodes with planar geometry have been fabricated on c-plane Al2O3 and investigated by current–voltage measurements. The effects of the in-plane conduction through the Si-doped ε-Ga2O3 layer on the diode performance and their relevance have been evaluated. A significant series resistance is observed, which shows typical features of the variable range hopping transport observed in Si-doped ε-Ga2O3; this in-plane transport mechanism is probably induced by the columnar domain structure of this polymorph. The dependence of the series resistance on the geometry of the diode supports the interpretation. A simple equivalent model is presented to describe the experimental behavior of the diode, supported by preliminary impedance spectroscopy investigation.