The Applications of Highly Doped Ge₁−𝑥Bi𝑥 Alloy Films in Near-Infrared Photodetectors and Photoresistor Logic Gates

Ge1-xBix films have garnered significant attention due to their exceptional light absorption capabilities in the near-infrared spectrum, making them suitable for use in optoelectronic devices. Most Ge1-xBix films employed in near-infrared photodetectors exhibit lower levels of bismuth (Bi) doping (x <18%). This study explores the potential applications of highly doped Ge1-xBix films in near-infrared optoelectronic devices. The Ge0.819Bi0.181 and Ge0.748Bi0.252 films, with varying concentrations of Bi doping, were used to fabricate Au/Ge0.819Bi0.181 and Au/Ge0.748Bi0.252 optoelectronic devices. Test results indicate that the Au/Ge0.819Bi0.181 photodetector exhibits high responsivity and specific detection in the near-infrared range of 800-1200 nm. Without an applied bias, the responsivity and specific detection can reach 2.17 A/W and 1.05 × 1013 Jones at 1000 nm, respectively, demonstrating excellent self-driving performance. Since the Au film has established a complete Ohmic contact with the Ge0.748Bi0.252 film, the Au/Ge0.748Bi0.252 device can primarily function as a photoresistor in the near-infrared spectrum. Furthermore, considering its output current characteristics at bias voltages of 3V and 5V at 1000 nm, the device can also operate as a photoresistor logic OR gate. This study highlights the potential of highly doped Ge1-xBix films for applications in near-infrared photodetectors and photocontrolled logic gates.