High carrier collection efficiency in graphene/GaAs heterojunction photodetectors

Abstract In the rapidly evolving field of modern technology, near-infrared (NIR) photodetectors are extremely crucial for efficient and reliable optical communications. The graphene/GaAs Schottky junction photodetector leverages graphene’s exceptional carrier mobility and broadband absorption, coupled with GaAs’s strong absorption in the NIR spectrum, to achieve high responsivity and rapid response times. Here, we present a NIR photodetector employing a graphene/GaAs Schottky junction tailored for communication wavelengths. We fabricated high-performance graphene/GaAs Schottky junction devices with interdigitated electrodes of varying finger widths, systematically investigating their impact on device performance. The experimental results demonstrate that incorporating interdigitated electrodes significantly enhances the collection efficiency of photogenerated carriers in graphene/GaAs photodetectors. When illuminated by 808 nm NIR light at an intensity of 7.23 mW/cm2, the device achieves an impressive switch ratio of 10⁷, along with a high responsivity of 40.1 mA/W and a remarkable detectivity of 2.89 × 10¹³ Jones. Additionally, the device is characterized by rapid response times, with rise and fall times of 18.5 and 17.5 μs, respectively, at a 3 dB bandwidth. These findings underscore the significant potential of high-performance graphene/GaAs photodetectors for applications in NIR optoelectronic systems.