Average Reset Research Articles

Enhanced Ga2O3-Based RRAM via Stacked Bilayer ZnO/Ga2O3

The stability and endurance of resistive random-access memory (RRAM) devices over long-term use has been widely acknowledged as a concern. Therefore, different top electrodes and oxygen concentration flows were used with stacked ZnO/Ga2O3 as the switching layer to enhance the performance of Ga2O3-based RRAM. All switching layers were deposited by radio frequency sputtering in this study, and the oxygen vacancies were well controlled by controlling the oxygen concentration flow. When a stacked structure was formed, the gradients in the concentration of oxygen vacancies and mobility influenced the set and reset processes. With the stacked structure, the average set voltage was 1.5 V, and the average reset voltage was −0.7 V. In addition, under DC sweeps, the stacked RRAM demonstrated a high operating life of more than 300 cycles. In conclusion, the performance and stability of RRAM can be enhanced by adjusting the concentration of oxygen vacancies using different compositions of elements.

Stability-Enhanced Resistive Random-Access Memory via Stacked In x Ga1-x O by the RF Sputtering Method.

The stability of a resistive random-access memory (RRAM) device over long-term use has been widely acknowledged as a pertinent concern. For investigating the stability of RRAM devices, a stacked InxGa1–xO structure is designed as its switching layer in this study. Each stacked structure in the switching layer, formed via sputtering, consists of varying contents of gallium, which is a suppressor of oxygen vacancies; thus, the oxygen vacancies are well controlled in each layer. When a stacked structure with layers of different contents is formed, the original gradients of concentration of oxygen vacancies and mobility influence the set and reset processes. With the stacked structure, an average set voltage of 0.76 V, an average reset voltage of −0.66 V, a coefficient of variation of set voltage of 0.34, and a coefficient of variation of reset voltage of 0.18 are obtained. Additionally, under DC sweeps, the stacked RRAM demonstrates a high operating life of more than 4000 cycles. In conclusion, the performance and stability of the RRAM are enhanced herein by adjusting the concentration of oxygen vacancies via different compositions of elements.

Reduced Operation Current of Oxygen-Doped ZrN Based Resistive Switching Memory Devices Fabricated by the Radio Frequency Sputtering Method

In this work, we report the feasibility of resistive switching (RS) properties of oxygen-doped zirconium nitride (O-doped ZrN) films with platinum (Pt) and platinum silicide (PtSi) bottom electrode (BE), produced by a sputtering method. Compared to O-doped ZrN using Pt BE, when Pt/p-Si was used as BE, the foaming voltage slightly increased, but the operation current was reduced by about two orders. In particular, the average reset current of the O-doped ZrN memory cells was reduced to 50 µA, which can delay deterioration of the element, and reduces power consumption. Therefore, the use of PtSi as the BE of the O-doped ZrN films is considered highly effective in improving reliability through reduction of operating current of the memory cells.

Investigation of Conductive Mechanism of Amorphous IGO Resistive Random-Access Memory with Different Top Electrode Metal

In this paper, resistive random-access memory (RRAM) with InGaO (IGO) as an active layer was fabricated by radio-frequency (RF) sputtering system and the resistive switching mechanism with the different top electrode (TE) of Pt, Ti, and Al were investigated. The Pt/IGO/Pt/Ti RRAM exhibits typical bipolar resistive switching features with an average set voltage of 1.73 V, average reset voltage of −0.60 V, average high resistance state (HRS) of 54,954.09 Ω, and the average low resistance state (LRS) of 64.97 Ω, respectively. Ti and Al were substituted for Pt as TE, and the conductive mechanism was different from TE of Pt. When Ti and Al were deposited onto the switching layer, both TE of Ti and Al will form oxidation of TiOx and AlOx because of their high activity to oxygen. The oxidation will have different effects on the forming of filaments, which may further affect the RRAM performance. The details of different mechanisms caused by different TE will be discussed. In brief, IGO is an excellent candidate for the RRAM device and with the aids of TiOx, the set voltage, and reset voltage, HRS and LRS become much more stable.

A Binomial Lattice model for Pricing Geometric Average Reset Options

A Binomial Lattice model for Pricing Geometric Average Reset Options

Impact of device size and thickness of Al2O 3 film on the Cu pillar and resistive switching characteristics for 3D cross-point memory application.

Impact of the device size and thickness of Al2O3 film on the Cu pillars and resistive switching memory characteristics of the Al/Cu/Al2O3/TiN structures have been investigated for the first time. The memory device size and thickness of Al2O3 of 18 nm are observed by transmission electron microscope image. The 20-nm-thick Al2O3 films have been used for the Cu pillar formation (i.e., stronger Cu filaments) in the Al/Cu/Al2O3/TiN structures, which can be used for three-dimensional (3D) cross-point architecture as reported previously Nanoscale Res. Lett.9:366, 2014. Fifty randomly picked devices with sizes ranging from 8 × 8 to 0.4 × 0.4 μm2 have been measured. The 8-μm devices show 100% yield of Cu pillars, whereas only 74% successful is observed for the 0.4-μm devices, because smaller size devices have higher Joule heating effect and larger size devices show long read endurance of 105 cycles at a high read voltage of -1.5 V. On the other hand, the resistive switching memory characteristics of the 0.4-μm devices with a 2-nm-thick Al2O3 film show superior as compared to those of both the larger device sizes and thicker (10 nm) Al2O3 film, owing to higher Cu diffusion rate for the larger size and thicker Al2O3 film. In consequence, higher device-to-device uniformity of 88% and lower average RESET current of approximately 328 μA are observed for the 0.4-μm devices with a 2-nm-thick Al2O3 film. Data retention capability of our memory device of >48 h makes it a promising one for future nanoscale nonvolatile application. This conductive bridging resistive random access memory (CBRAM) device is forming free at a current compliance (CC) of 30 μA (even at a lowest CC of 0.1 μA) and operation voltage of ±3 V at a high resistance ratio of >104.

Pricing an Arithmetic Average Reset Option Using the Green Function Method

This study investigates the pricing of the arithmetic average reset option. The option price is formulated as the solution of the Black-Scholes equation. In addition, the valuation is derived from a series of initial value problems based on the Green function through integration. Finally, the reset option price is numerically calculated. Throughout the numerical method, we can derive reset option prices of both arithmetic average and geometric average reset options. This study also presents the numerical examples for comparison.

On pricing arithmetic average reset options with multiple reset dates in a lattice framework

We develop a straightforward algorithm to price arithmetic average reset options with multiple reset dates in a Cox et al. (CRR) (1979) [10] framework. The use of a lattice approach is due to its adaptability and flexibility in managing arithmetic average reset options, as already evidenced by Kim et al. (2003) [9]. Their model is based on the Hull and White (1993) [5] bucketing algorithm and uses an exogenous exponential function to manage the averaging feature, but their choice of fictitious values does not guarantee the algorithm’s convergence (cfr., Forsyth et al. (2002) [11]). We propose to overcome this drawback by selecting a limited number of trajectories among the ones reaching each node of the lattice, where we compute effective averages. In this way, the computational cost of the pricing problem is reduced, and the convergence of the discrete time model to the corresponding continuous time one is guaranteed.

The Multi-Million-Dollar Question

The complexity of net interest margin (NIM) securities, coupled with the fact that they tend to be private placements, keeps this a rather thinly traded market, and frequently the NIMs that come to the secondary market do not trade as efficiently as other types of securities with similar complexity and risk. Risks for holders of NIMs relate to losses on the underlying portfolio, leverage of the transaction, prepayments, collateral performance, movements in the yield curve, and trading efficiency. The holder should question the NIM structure, current and expected over-collateralization levels, the seasoning of the deal, the step-down date, credit profiles of underlying borrowers, the percentage of collateral with fixed and floating rates, the average excess spread amount for fixed-rate collateral, the average reset date for floating-rate collateral, and prepayment, delinquency, recovery and loss rates. <b>TOPICS:</b>Credit risk management, volatility measures

Pricing options with American-style average reset features

This study extends the Hull and White (1993 J. Derivatives 1 21–31) binomial method to construct a trinomial model for the valuation of American-style options whose strike price can be reset to a new level. The reset criterion is conditioned upon the average underlying asset price hitting the reset barrier in a specified period although the model proposed can accommodate other features. For prices benchmarked against ordinary Asian options, we investigate the difference between a daily reset warrant and a period-average reset warrant and find that the number of time steps between observations affects the value of American-style average price options and period-average reset options.

Valuation of Arithmetic Average Reset Options

Options whose payoffs are based on an arithmetic average of the price of the underlying can have some useful advantages over standard options. The payoff is less susceptible to manipulation of the price at expiration, and in many cases a hedger is more interested in locking in the average value of some cost or price over a period of time than in fixing it as of a specific date. For reset options, whose strike prices may be reset at fixed dates depending on the value of the underlying, arithmetic averaging substantially reduces the problem that the option9s delta can jump on the reset date. However, arithmetic averaging of lognormally distributed random variables produces a substantial problem for valuation, because the underlying average is not lognormal. In this article, Kim, Chang, and Byun provide an effective valuation methodology for arithmetic average reset options.

Pricing Arithmetic Average Reset Options With Control Variates

Stock markets around the world have fallen sharply in recent years, leaving many stock options that were issued in better times deep out of the money. Some firms with employee stock options outstanding have chosen simply to adjust the strikes downward, toward current market levels. Reset options offer this kind of protection automatically, by specifying one or more stock price levels at which the option9s strike price will be reset. Liao and Wang examine the problem of pricing reset options, taking into account some real-world features, including multiple reset levels and arithmetic Asian payoffs, that may be present but present difficulties for valuation. They show how a standard reset contract may be valued as a package of barrier options, and they offer a control variate technique for Asian contracts. One important feature of reset options is the fact that delta is discontinuous at the reset points.