BWO and IMPATT Millimeter Wave Probing of c-Si, and Perovskite

In this paper, we provide a short review of electrovacuum microwave generator “carcinotron” (backward wave oscillator, BWO) and other microwave sources that are used for materials characterization. Time averaged photoresponse transients of c-silicon, and hybrid perovskite obtained using electrovacuum probe source BWO are compared with photo-responses of the same samples using solid-state Impact Ionization Avalanche Transit-time (IMPATT) diode cavity oscillator probe. We discuss outcomes of using two different probing sources operated at 140 GHz. IMPATT probe source yields a slightly higher crest factor than the BWO source as evidenced from perovskite response to light, and no systematic relationship was found between mmw transmissivity and stimulating laser (pump) fluence.