Resistive switching （RS） behaviors of Dy2O3- based memory devices with and without Pt nanocrystals （Pt-nc） layer were investigated for nonvolatile memory applications. The Cu/Pt-nc/Dy2O3/Pt memory exhibits excellent unipolar RS characteristics, including highly uniform switching parameters, lower switching voltage （〈1.2 V）, high resistance ratio （〉1 × 104）, a large number of switching cycles, as well as long retention time （〉1 × 105 s）, owing to the local electric field confined and strengthened near the nanocrystals＇ location.
Hong-Bin ZhaoHai-Ling TuFeng WeiXin-Qiang ZhangYu-Hua XiongJun Du
The band alignment of HfO2 film on p-type （100） InP substrate grown by magnetron sputtering was investigated.The chemical states and bonding characteristics of the system were characterized by X-ray photoelectron spectroscopy （XPS）.The results show that there is no existence of Hf-P or Hf-In and there are interfacial In2O3 and InPO4 at the interface.Ultraviolet spectrophotometer （UVS） was employed to obtain the band gap value of HfO2.In 3d and Hf 4f core-level spectra and valence spectra were employed to obtain the valence band offset of HfO2/InP.Experimental results show that the （5.88 ± 0.05） eV band gap of HfO2 is aligned to the band gap of InP with a conduction band offset （△Ec） of （2.74 ± 0.05） eV and a valence band offset （△Ev） of （1.80 ± 0.05） eV.Compared with HfO2 on Si,HfO2 on InP exhibits a much larger conduction band offset （1.35 eV larger）,which is beneficial to suppress the tunneling leakage current.
Effects of NH3 rapid thermal annealing （RTA） on the interface and electrical properties of Gd-doped HfO2 （GDH）/Si stack were investigated. The process of NH3 annealing could significantly affect the crystallization, stoichiometric properties of GDH film and the interface characteristic of GDH/Si system. NH3 annealing also led to the decrease of interface layer thickness. The leakage current density of Pt/GDH/p-Si MOS capacitor without RTA was 2× 10-3 A/cm2. After NH3 annealing, the leakage current density was about one order of magnitude lower （3.9× 104 A/cm2）. The effective permittivity extracted from the C-V curves was -14.1 and 13.1 for samples without and with RTA, respectively.
