High external quantum efficiency in ZnO/Au/Ga2O3 sandwich–structured photodetector

In this study, sandwich–structured photodetector (SSPD), a new type of structure of PD based on traditional metal–semiconductor–metal (MSM) structure, was designed and fabricated to solve the difficult problem of weak light detection caused by the low gain of PDs with the traditional structure. Herein, zinc oxide/gold/gallium(III) oxide (ZnO/Au/Ga2O3) SSPD with a high external quantum efficiency (EQE) was successfully constructed by growing Ga2O3 film layer on the electrode area of the ZnO/Au MSM–structured device. The high EQE originates from the backlight–type irradiation and embedded electrodes of the special sandwich structure existing in the ZnO/Au/Ga2O3 SSPD. The ZnO/Au/Ga2O3 SSPD shows EQE of up to 11626 % at 30 V, which is 18 times (654 %) higher than that of the traditional MSM–structured ZnO/Ga2O3/Au PD. These results indicate that the research provides a new and effective method to increase the performance of Ga2O3–based PDs.