Experimental and theoretical study of capacitive memory of metal-oxide-semiconductor devices based on Er-doped In_2O_3 nano-column arrays

摘要

The enhanced electronic memory performance of glancing angle deposited erbium-doped indium oxide (In_2O_3∶Er) transparent nano-column (NCol) based metal-oxide-semiconductor (MOS) structured memory devices is reported. The fabricated MOS devices are Au/ In_2O_3/p-Si, Au/0.26 at. % In_2O_3∶Er/p-Si, and Au/0.48 at. % In_2O_3∶Er/p-Si. The capacitance-voltage (C-V), conductance-voltage (G-V), C-V hysteresis, endurance, and retention properties from the cyclic current-voltage (I-V) curve of the fabricated devices were investigated in detail. The overall interface state density (D_(it)) for the devices at the different applied frequency (f) decreases with the increase in Er doping. The observations obtained from C-V, G-V, and D_(it)-f curves were theoretically explained considering a modified delta depletion model. It was found that Au/0.48 at. % In_2O_3∶Er/p-Si does not go to inversion even at a high applied voltage. The constant capacitive memory window (MW) for Au/In_2O_3/p-Si is ～1 V at the depletion region. MW increases from ～0.6V (sweep voltage ±6V) to ～2.5 V (sweep voltage ±16 V) and ～1.4V (sweep voltage ±6V) to ～6.8 V (sweep voltage ±16 V), respectively, for Au/0.26 at. % In_2O_3∶Er/p-Si and Au/ 0.48 at. % In_2O_3∶Er/p-Si. The increased MWs despite reduced D_(it) is explained in detail by primarily considering increased polarization switching of the In-O-Er material, asymmetric charge injection from the top electrode, and the presence of the oxygen-rich environment. The I-V hysteresis performance of the devices under a reverse bias was also improved with Er doping due to the migration of O~(2-) inside the oxide layer. The whole analysis indicates that the gate-controlled Au/0.48 at. % In_2O_3∶Er/p-Si MOS device is appropriate for capacitive memory applications.