This study investigates the resistive switching behavior of Pt, Al, and Cr electrodes for ZnO-based resistance random access memory. Results show that the existence of oxygen ions in the electrode plays an important role in the resistive switching behavior during filament reduction and oxidization. The Cr/ZnO/Pt structure exhibited a significant improvement in resistive switching parameters such as operation voltages and resistance states. This is most likely due to the partial formation of oxidation layers, namely CrO x at the Cr/ZnO interface. These layers act as oxygen reservoir or oxygen supplier, and improve the efficiency of oxygen ion exchange near the electrode/oxide interface.Resistance random access memory (RRAM) has attracted considerable attention because of its potential as a replacement for flash memory in next-generation nonvolatile memory (NVM) applications. 1 The typical configuration of RRAM includes a metal/insulator/metal structure, and its operation is based on the switching of the high resistance state (HRS) and the low resistance state (LRS) (off and on state) under a large bias. Switching can be classified into two types based on I-V behaviors: bipolar and unipolar. 2 Bipolar resistive switching shows directional resistive switching, depending on the polarity of the applied voltage. Unipolar resistive switching depends on the amplitude of the applied voltage without polarity. The resistive switching behaviors were observed from various materials, such as binary oxides, perovskite oxides, and chalcogenide materials. [1][2][3][4][5][6][7] Zinc oxide (ZnO) has many characteristics ideally suited for optics and electronics, such as a wide bandgap of approximately 3.37 eV, adjustable electronic properties by doping with different dopants, and low synthetic temperature. 8 Recent research shows that ZnObased thin films have promising resistive switch characteristics. [9][10][11][12][13][14] The unipolar switching characteristics of ZnO usually appear in symmetric electrode structures such as Pt/ZnO/Pt, 9 ITO/ZnO/ITO, 10 and Al/ZnO/Al devices. 11 Bipolar switching characteristics have also been observed in TiN/ZnO/Pt, 12 Ag/ZnO:Mn/Pt, 13 and ITO/ZnO:Mg/FTO devices. 14 However, research into the influence of electrode material on the resistive switching behavior of ZnO films is lacking.Among the various resistive switching mechanisms, the formation of localized conductive paths (filaments) is one of the most widely accepted. However, the localized conductive paths in thin films are diverse in each switching, leading to the nonuniform distribution of switching voltages and resistance states. This in turn results in irresolvable errors during RRAM operation. Thus, effectively improving the stability of switching behavior is an essential issue for practical RRAM applications. Researchers have proposed methods to improve this problem, such as embedding Pt nanocrystals in TiO 2 films, 15 embedding thin Al layers between HfO 2 and electrode layers, 16 and Al doping in ZrO 2 films. 17 The current study in...

Charge storage characteristics of metal-oxide-semiconductor (MOS) structure containing Au nanocrystals on tunnel oxide composed of triply stacked SiO2, HfO2, and Al2O3 layers were studied. Significantly high charge injection and detrapping efficiency for program and erase operations along with a satisfactory long-term charge retention were obtained from the above MOS structure. It is attributed to the bandgap engineering of tunnel oxide with a multistacked concave barrier, from which the effective thickness of the tunneling barrier can be greatly reduced under a moderate bias, while a thick and high barrier is retained for charge retention.

The atomic layer deposition ͑ALD͒ of Al 2 O 3 using trimethylaluminum ͑TMA͒ as a metal precursor on an InSb substrate with or without surface pretreatments was investigated. It was found that both in situ TMA/Ar purging ͑half-ALD cycle͒ and ex situ CP4A ͑HNO 3 :HF:CH 3 COOH:H 2 O = 2:1:1:10͒ chemical etching can remove the native oxides on InSb before ALD of Al 2 O 3 , and lead to a native-oxides-free Al 2 O 3 /InSb structure. Characteristics of current density-voltage and capacitance-voltage were also investigated to evaluate the insulative and interface quality in a Pt/Al 2 O 3 /InSb metal-oxide-semiconductor structure.

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ALD HfZrO high-K fabricated by novel multi deposition multi annealing (MDMA) technique at room temperature in Ultraviolet-Ozone (UVO) ambient is systematically investigated for the first time via both physical and electrical characterization. As compared to the reference gate stack treated by conventional rapid thermal annealing (RTA) @ 600 o C for 30 s (with PVD TiN electrode), the devices receiving MDMA in UVO demonstrates: 1) more than one order of magnitude leakage reduction without EOT penalty at both room temperature and an elevated temperature of 125 o C; 2) much improved stress induced degradation in term of leakage increase and flat band voltage shift (both room temperature and 125 o C); 3) enhanced dielectrics break-down strength and time-dependant-dielectric-breakdown (TDDB) life time. The improvement strongly correlates with the cycle number of deposition and annealing (D&A, while keeping the total annealing time and total dielectrics thickness as the same). Scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) analysis suggest both oxygen vacancies (V o ) and grain boundaries suppression in the MDMA treated samples are likely responsible for the device improvement. The novel room temperature UVO annealing is promising for the gate stack technology in a gate last integration scheme.