  GeAs is a layered material of the IV-V groups that is attracting growing
attention for possible applications in electronic and optoelectronic devices.
In this study, exfoliated multilayer GeAs nanoflakes are structurally
characterized and used as the channel of back-gate field-effect transistors. It
is shown that their gate-modulated p-type conduction is decreased by exposure
to light or electron beam. Moreover, the observation of a field emission
current demonstrates the suitability of GeAs nanoflakes as cold cathodes for
electron emission and opens up new perspective applications of two-dimensional
GeAs in vacuum electronics. Field emission occurs with a turn-on field of ~80
V/{\mu}m and attains a current density higher than 10 A/cm^2, following the
general Fowler-Nordheim model with high reproducibility.
