  Deep understanding of plasmonic nanoparticles (PNPs)-light interaction over
semiconductors surface shows great promises in enhancing their optoelectronic
devices efficiency beyond the conventional limit. However, PNP-light
interaction critically decided by the distribution density of PNPs over the
semiconductor surface which is not entirely understood. Here, a systematic
study depicting how the interparticle gap between Silver (Ag) NPs influences
the performance of the \b{eta}-Ga2O3 based solar-blind photodetector.
Interestingly, a remarkable transition is observed, where the varied
interparticle gap not only changes the polarity but also reverses the
traditional photodetector behaviour. The positive transient response of bare
\b{eta}-Ga2O3 photodetector with feeble DUV light switches its behaviour
remarkably to 20 times enhance negative-photoresponse when decorated by
sparsely-spaced Ag-PNPs with ultra-high responsivity of 107.47 A/W at moderate
power and an incredible report-highest responsivity of 4.29 mA/W on single
semiconducting \b{eta}-Ga2O3 layer at self-powered mode. Moreover, as the
density of the Ag-PNPs was further increased, the photocurrent decreases with
illumination which dynamically reverses the traditional photodetector to
unnatural anomalous effect. In particular, our study represents the first
demonstration of plasmonic tuning effect to two active dynamic switching modes;
i.e. reverse switchable and anomalous behaviour, the fundamentals of which have
not studied experimentally yet. Finally, we propose a unified well-explained
model to rationalize all observed experimental trends while set-up fundamental
basis for establishing potential applications.
