Fig. 3: The tunneling pathway and charge injection behavior for edge or top contacted flash memory.
Illustration of the energy band diagram for charge injection during program operation in a edge and b top contacted memory cells, the tunneling pathways through contact region and semiconductor channel are compared (M: metal contact, CH: channel, CA: contact affected area). When considering the band bending in semiconductor channel (Φs) under field modulation, the hole tunneling barrier (\( {\varPhi }_{\tt{tB}}^{\tt{h}}\)) though the valance band of hBN is apparently reduced from the initial value (\( {\varPhi }_{{\tt{tB0}}}^{\tt{h}}\)). If compared to the field emission (indicated by red arrow) in edge contact, rich trap states under contact affected area (CA) in top contact configuration lead to thermionic process governed charge emission at contact (blue arrow). c Capacitance-voltage characteristic and d temperature-dependent charge injection behavior of edge and top contacted memory cell. The measured capacitance is intepreated using the inset equialivent circuit, which considers capacitance associated with interface states (Cit), semiconductor channel (Cs), and hBN dielectric layer (ChBN). d The charge injection efficiency is reflected by the threshold shift under ultrafast (10 ns) P/E operation, in which the pulse amplitude are respectively −15 V and 20 V for program and erase. Their distinct temperature dependence is indicated by the dash guidelines.
