Cascaded Photo-carrier Multiplication in Graphene-Oxide-Semiconductor (GOS)

Carrier multiplication (CM) is a fundamental mechanism that dictates the intrinsic gain or amplification in electronic and optoelectronic devices. Integrating 2D materials with bulk (3D) semiconductors allows enhanced CM and carrier transport pathways often not observed in conventional devices. Recent studies have demonstrated the potential of graphene-oxide-semiconductor (GOS) structures in ultrafast and broadband image sensing. This study investigates the multi-stage carrier multiplication of photoexcited carriers in GOS samples under deep depletion (DD). We observed that the multiplication factor is larger than 200 under pulsed light excitation, presumably due to two-stage cascaded carrier multiplication in SiO2 and the depletion region in Si. This study reveals a spectrum of carrier generation and multiplication mechanisms in the GOS device scheme that were hitherto not reported before.