Fig. 1
From: Critical band-to-band-tunnelling based optoelectronic memory
Critical BTBT in BP on InSe devices. a Schematic diagram of the critical BTBT memory. b Transfer characteristics of the critical BTBT memory (red line) and a BP transistor (blue line). c Negative photomemory characteristics of the critical BTBT memory in response to multiple 520 nm laser pulses with a duration of 500 ns. Inset: Demonstration of the 500 ns laser pulse width. In d–g, band alignments are depicted at Vg < 0 with a constant Vd. d Photoresponse mechanism under the critical BTBT condition. Photo-injected electron-hole pairs are separated by a tilted energy band in InSe, and electrons further tunnel into BP, preventing recombination. e Mechanism of hole recombination suppression under the critical BTBT condition. The region where electrons in BP can tunnel to InSe is separated in space from the region where holes are stored, avoiding the recombination with stored holes in InSe. f Schematic of the photoresponse mechanism when the valence band in the channel is below the critical BTBT condition. Electrons in the conduction band in the gate have no final state to tunnel to. Both electrons and holes are stored in the gate, resulting in severe recombination. g Recombination mechanism of stored holes when the valence band in the channel is above the critical BTBT condition. A higher valence band in the channel allows the tunnelling of electrons to deep into the gate. The tunnelling region overlaps with the region occupied by stored holes, causing recombination. f and g refer to the energy band diagrams of other heterogeneous interfaces that do not satisfy critical BTBT conditions
