Abstract
Monoclinic Ga2O3 (β-Ga2O3) films were grown on Si/SiO2 by using MOCVD. Then, we fabricated the solar-blind photodetector with a back-gate MOS structure. The device exhibited obvious photoresponse under 254-nm UV light illumination, and the photocurrent increased by five orders of magnitude, which could be controlled by VGS. The current generated under dark conditions could also be regulated by VGS and tended to constant when the regulation of VGS was reaching saturation. Meanwhile, VGS was confirmed to have a certain ability to regulate the photocurrent. The present device demonstrated excellent stability and fast response (rise) and recovery (decay) times under the 254-nm light illumination as well as a responsivity of 417.5 A/W, suggesting a valuable application in solar-blind UV photodetectors.
Highlights
Owing to their wide bandgap (∼4.9 eV) and stable chemical and physical properties, β-Ga2O3 thin films have been investigated for use as ultraviolet (UV) photodetectors (PDs) (Kokubun et al, 2007; Oshima et al, 2008)
The β-Ga2O3 film has uniformly grown on the Si/SiO2 substrate using the metal organic chemical vapor deposition (MOCVD) growth method
The results suggest that the MOS transistor becomes on-state when VGS > 20 V and the IDS can be controlled by VGS; in other words, the typical three-terminal MOS structure fin field transistor (FET) can enhance the sensitiveness and responsivity with photoelectron regulation by adjusting the drain voltage and gate voltage
Summary
Owing to their wide bandgap (∼4.9 eV) and stable chemical and physical properties, β-Ga2O3 thin films have been investigated for use as ultraviolet (UV) photodetectors (PDs) (Kokubun et al, 2007; Oshima et al, 2008). A solar-blind UV PD with a back-gate MOS structure was fabricated, and the photoresponse behaviors based on different applied voltages under dark and illumination conditions were characterized. Such detectors with a back-gate MOS structure fabricated on β-Ga2O3 films show high responsivity and fast response times, which can be regulated by adjusting the gate voltages and drain voltages. According to the Schottky–Mott rule, the metal–semiconductor (MS) interface barriers of Ti/β-Ga2O3 are approximately 0.33 eV, suggesting an approximate Ohmic contact between metal Ti and semiconductor β-Ga2O3 It ensures that the electrode contact will not interfere with the photoelectric performance of the device as much as possible.
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