Figure 1: Characteristics and mechanisms of charge conductions in metal/insulator/cathode buffer layer/metal (MICM) structures.
From: Direct electron injection into an oxide insulator using a cathode buffer layer
(a) Schematic structure of the MICM device consisting of P++-Si anode/insulator 200-nm SiO2/6-nm ZnO/Al cathode. (b–d) Current density-voltage characteristics of the MICM devices employing a thermally grown 200-nm SiO2 as the insulator; (b) with (red solid line) and without (blue solid line) the CBL; (c) under various temperature (T) conditions (symbols); (d) depending on the thickness of the SiO2 layer (symbols) at T=292 K. In c and d, green solid lines indicate theoretical fitting results to the measured curves using equation (1) with fitting parameters shown in Supplementary Table 1. (e,f) Schematic of current-rectifying mechanisms of the MICM device, when: (e) V>0, current flows by space-charge-limited currents (SCLCs) of electrons injected from the metal cathode; (f) V<0, charge injection processes are not allowed, and then there are no available space charge currents.
