Ultrathin Fluorescent Nanodiamond Films for Nanoscale Quantum Sensing in Operando Semiconductor Devices

Abstract Nanoscale quantum sensing is playing an increasingly critical role across diverse areas of research, particularly in the rapidly evolving field of semiconductor nanoelectronics. In this work, ultrathin fluorescent nanodiamond (FND) films are developed to function as quantum sensors for in operando measurements of magnetic fields and temperature in semiconductor devices. FNDs are electrically insulating carbon nanomaterials containing nitrogen‐vacancy (NV) centers, renowned for their exceptional photostability and distinctive quantum properties. An electrospray deposition method is first established to produce uniform, near‐monolayer FND films on bipolar junction transistors (BJTs) and field‐effect transistors (FETs) without compromising their performance. Then, optically detected magnetic resonance (ODMR) is employed to detect magnetic fields and monitor temperature increases as electrical currents are passed through the FND‐coated semiconductor chips. Finally, we introduce a technique called FND‐based lock‐in photoluminescence (PL) thermography, which enables wide‐field, real‐time temperature sensing and imaging of these actively operating BJTs and FETs with nanometric spatial and millisecond temporal resolution. In comparison to ODMR, this innovative PL thermography method offers enhanced practicality and ease of implementation, making it well‐suited for diagnostic applications in semiconductor devices.