Photo detection through bilayer graphene/ZnO/Si dual heterojunctions covering the spectrum from ultraviolet to near infrared

Diverse applications of high-performance photodetectors have attracted a significant research interest. In recent years it has been part of various electronics circuits ranging from environmental monitoring to communication systems. In this article, impact of bilayer-graphene (BLG)/zinc oxide (ZnO)/silicon (Si) based dual heterojunction is investigated for advanced ultra-violet (UV) to near infrared (NIR) photo detection. Toward the creation of synergistic heterojunction, a novel blend of P-type BLG, N-type ZnO, and N-type Silicon is used. The unique properties of graphene, scalability of silicon substrate, wide energy band gap of ZnO has leveraged the dual heterojunction for the optimum carrier transport and light absorption characteristics of UV to NIR detector. The Silvaco Atlas TCAD software is employed for the design and analysis of the photodetector. The simulation results demonstrate superior performance, with a low dark current density (Jdark) of 0.66 pA/cm2, better photocurrent density (Jlight) of 0.25 µA/cm2 along with a remarkable Jlight/Jdark ratio of 3.7×105, 3-dB cut-off frequency of 0.16 THz, “external-quantum-efficiency” of 69.04%, photocurrent-responsivity of 0.24 A/W, detectivity of 5×1014 cmHz1/2/W, and rapid response time of 2.2 ps at a bias of –0.5 V. The study contributes to UV-to-NIR photodetection technology, showing the BLG/ZnO/Si dual heterojunction as a single framework promising candidate for high-performance UV-to-NIR photodetectors opens paths for the future development of advanced sensing technologies.