Energy‐Band Engineering by Remote Doping of Self‐Assembled Monolayers Leads to High‐Performance IGZO/p‐Si Heterostructure Photodetectors

Metal oxide semiconductors are of great interest for enabling advanced photodetectors. However, operational instability and the absence of an appropriate doping technique hinder practical development and commercialization. Here, a strategy is proposed to dramatically increase the conventional photodetection performance, having superior stability in operational and environmental atmospheres. By performing energy‐band engineering through an octadecylphosphonic acid (ODPA) self‐assembled‐monolayer‐based doping treatment, the proposed indium–gallium–zinc oxide (IGZO)/p‐Si heterointerface devices exhibit greatly enhance the photoresponsive characteristics, including a photoswitching current ratio with a 100‐fold increase, and photoresponsivity and detectivity with a 15‐fold increase each. The observed ODPA doping effects are investigated through comprehensive analysis with X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and Kelvin probe force microscopy (KPFM). Furthermore, the proposed photodetectors, fabricated at a 4 in. wafer scale, demonstrate its excellent operation robustness with consistent performance over 237 days and 20 000 testing cycles. A proposed octadecylphosphonic acid (ODPA)‐treated indium–gallium–zinc oxide (IGZO)/p‐Si heterostructure photodetector exhibits an excellent on/off current ratio of 4 × 103 and unique negative differential resistance (NDR) current behavior, after implementation with a simple annealing process. Uniformity tests using 156 photodiodes and a 20 000 cycle test demonstrate the reliability of the proposed photodiode.