Effect of Post Metallization Annealing for La 2 O 3 Thin Film

3.4.2.5 The comparison with the case of Aluminum ElectrodesAs a summary of PMA with gold upper electrodes, the difference ofbehavior after thermal process was described. The C-V characteristics afterPDA/PMA compared to As-deposition are shown in Figure 3-50 and Figure3-51 respectively. It should be noted that although PDA with aluminumupper electrodes yielded a huge VFB shift toward negative side, PDA withgold upper electrodes almost did not yield any VFB shift. This resultindicates that La2O3 thin films might react with aluminum upper electrodesthe moment both came into contact. In the same way, although PMA withaluminum upper electrodes yielded a recovery of the VFB shift but also adecrease of the capacitance value, PMA with gold upper electrodes yieldedjust a little VFB shift and, on the contrary, an increase of the capacitancevalue. From these phenomena, it can be suggested that the choice of metalupper electrodes would exert an enormous influence on the electricalcharacteristics regardless of PDA or PMA, and the key of the solution of amatter of grave concern with the electrical characteristics of La2O3 would beincluded in this reaction which recovers VFB shift, but also decrease thecapacitance value.Capacitance (µF/cm 2 )2PDA400 o CAs-depo.Al1PDA400 o CAu0-2 -1 0 1 2Voltage (V)Figure 3-50: The comparison of electrical behavior after PDAbetween gold and aluminum upper electrodes.- 73 -