(a) Schematic representation of the FET device used in this work. (b) Schematic diagram of the interaction between the trapped electron and the percolation pathways mediated by the MW field (top). Multilevel RTN events recorded in the FET current measured at 80 K (bottom). (c) Wideband CW microwave spectroscopy of the FET channel current performed at 4.2 K. Each narrow spike is a separate resonance that is resolved into a Fano or Lorentzian shape at higher resolution (inset). (d) Density of states (red), amplitude change (blue) and coherence times (inset) histograms.