  We demonstrate self-powered \b{eta}-Ga2O3 deep-UV metal-semiconductor-metal
(MSM) photodetectors (PD) with 0.5% external quantum efficiency (EQE) at zero
bias. 150 nm thick (-201)-oriented epitaxial \b{eta}-Ga2O3-films were grown on
c-plane sapphire using plasma-assisted MBE. Ni/Au and Ti/Au metal stacks were
deposited as contacts to achieve asymmetric Schottky barrier heights in
interdigitated finger architecture for realizing self-powered photodetectors.
Current-voltage characteristics (photo and dark), time-dependent photocurrent
and spectral response were studied and compared with conventional symmetric MSM
PD with Ni/Au as the Schottky metal contact, fabricated on the same sample. The
asymmetric, self-powered devices exhibited solar-blind nature and low dark
current < 10 nA at 15 V with high photo-to-dark current ratio of ~ 103. The
dark and photocurrents were asymmetric with respect to the applied bias and the
responsivity in the forward bias was characterized by gain. The detectors
(asymmetric-MSM) were found to exhibit a responsivity of 1.4 mA/W at 255 nm
under zero-bias condition (corresponding to an EQE ~ 0.5 %), with a
UV-to-Visible rejection ratio ~ 102 and ~105 at 0 V and 5 V respectively.
