Sensing Electric Currents in an a-IGZO TFT-Based Circuit Using a Quantum Diamond Microscope

Quantum diamond microscopy (QDM), based on nitrogen-vacancy centers in diamond, offers a new approach for non-invasive magnetic imaging and diagnostics of electronic circuits under ambient conditions [1,2]. By detecting magnetic fields generated by on-chip currents, QDM can probe device regions that are inaccessible to conventional electrical methods. It enables reconstruction of current density maps with sub-micron spatial resolution and sensitivity down to sub-microampere currents [3,4]. Here, we employ a home-built QDM to map current flow in amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistor (TFT) circuits, a key technology for flexible and transparent electronics [5]. For demonstration, we used the QDM to map magnetic fields produced by currents flowing through an a-IGZO TFT-based current mirror circuit. The corresponding current density was reconstructed, enabling direct visualization of current pathways, including internal regions inaccessible to conventional electrical probing. This study establishes QDM as a novel and powerful diagnostic tool for evaluating oxide semiconductor-based circuits and emerging semiconductor technologies.

 

References:

[1] Levine, E. V. et al., Nanophotonics, 8 (11), 1945–1973 (2019).

[2] Scholten S. C. et al. J. Appl. Phys. 130, 150902 (2021)

[3] Basso, L. et al., Nanotechnology 34 015001 (2023).

[4] Garsi, M. et al., Phys. Rev. Applied 21, 014055 (2024).

[5] Khan, M.Y.A, Dubey, P. et al.,  arXiv:2506.17742 (2025)