Energy Band Modulation and Solar‐Blind Photoresponse Extension Based on (Sn_<i>x</i>Ga_1−<i>x</i>)₂O₃

Ultrawide‐bandgap gallium oxide (Ga 2 O 3 ) is capable of filtering out visible light and selectively responding to the solar‐blind ultraviolet light. However, the excessively wide bandgap results in a relatively narrow detection range, which limits the operational spectrum of the device. The intentional introduction of other elements to modulate the energy band of Ga 2 O 3 can effectively expand its detection range. Among these, Sn is considered an ideal exotic atom due to its similar electronic structure and atomic radius to Ga, as well as its lower activation energy. Here, we prepared (Sn x Ga 1− x ) 2 O 3 films by using plasma‐enhanced chemical vapor deposition. As the content of Sn elements increases, the absorption edge gradually shifts from 254 to 373 nm and the corresponding optical bandgap significantly decreases from 4.92 to 3.32 eV. Additionally, the changes in band structure calculated based on first‐principles calculations are consistent with the experimental results. Furthermore, optical characterization confirms that the introduction of Sn elements significantly increases the concentration of oxygen vacancies, which results in the photocurrent of photodetectors based on (Sn x Ga 1− x ) 2 O 3 being significantly increased by six orders of magnitude compared to intrinsic Ga 2 O 3 devices. This work proposes a new approach for the realization of high performance solar‐blind detectors with a wide response range.