Effect of thermal annealing on properties Ga$_2$O$_3$/GaAs:Cr heterostructures

Data on the sensitivity of Ga$_2$O$_3$/GaAs:Cr heterostructures are presented to long-wave and UV ($\lambda$ = 254 nm) radiation. The samples were obtained by RF magnetron sputtering of a gallium oxide film on non-heated GaAs:Cr substrates. Gallium arsenide plates with a Ga$_2$O$_3$ film were divided into two parts: one half was not annealed, and the other was annealed in argon at 500$^\circ$C for 30 min. Regardless of the presence or absence of heat treatment, the studied structures exhibit a photovoltaic effect and are able to operate in an autonomous mode. It is shown that a noticeable sensitivity to long-wave radiation appears in the samples only after thermal annealing of gallium oxide films. The response and recovery times of such UV radiation detectors do not exceed 1 second.