UV Detectors Based on In₂O₃–Ga₂O₃ Composite Films

The photoelectric and structural properties of In2O3–Ga2O3 composite films deposited by halide vapor phase epitaxy on sapphire substrates were investigated. The deposited films were a composite of cubic c-In2O3 and
$\delta $
-Ga2O3 phases with a low content (Inx
${\mathrm {Ga}}_{{1}-\text {x}}$
)2O2.4 solid solution deficient in oxygen phase at the surface region. The spectral dependencies of the responsivity, external quantum efficiency, and detectivity were studied in the wavelength interval from 205 to 360 nm. The In2O3–Ga2O3 composite films demonstrated high photosensitivity, low base resistance, and wide spectral interval of sensitivity, including UV-C, UV-B, and UV-A wavelength ranges. The maximum external quantum efficiency and responsivity of the In2O3–Ga2O3 composite films achieved under radiation exposure at a wavelength of 214 nm and electric field strength of 1 kV/cm were
$3.8\times 10^{{5}}$
% and 660 A/W, respectively. A mechanism for the high photosensitivity of the In2O3–Ga2O3 composite films based on the bipolar generation of charge carriers mainly in the segregated regions of the
$\delta $
-Ga2O3 phase is proposed.