Charge Trapping and Decay Mechanism in Post Deposition Annealed Er2O3 MOS Capacitors by Nanoscopic and Macroscopic Characterization

In this paper, the charge trapping and decay mechanism is investigated in post deposition rapid thermal anneal (RTA) and furnace anneal (FA) erbium oxide (Er₂O₃) ultrathin films by Kelvin probe force microscopy (KPFM) technology. The trap density is calculated by the contact potential difference measurements obtained from KPFM. Furthermore, it is compared with the trap density calculated from the electrical measurements for Er₂O₃ MOS capacitors to give an insight on the reliability of KPFM for trap density estimation. Experimental results showed that post deposition RTA treatment results in higher trapping as compared to FA treatment on Er₂O₃ ultrathin films. It was observed that vertical charge leakage plays a dominant role in Er₂O₃ as compared to lateral charge spreading. The space-charge-limited conduction mechanism was observed in Er₂O₃ MOS capacitors, which was used to study the charge injection and decay mechanism. This investigation may help to fill the trap density computation gaps between nanoscopic KPFM and macroscopic capacitance-voltage-based electrical measurements for nanoscale MOS-based applications.