A bidirectional converter operated by dual phase-shift switching strategy is proposed. The advantages include two directions of power flow ability, a wide output voltage range, and zero voltage ...switching. In contrast with conventional single phase shift method, the proposed method is capable of decreasing the reactive power caused by cycling current. In order to verify the feasibility of the proposed idea, this paper implements a dual-active bridge converter with a maximum power 500W to verify the proposed idea. The experimental results show that it is indeed capable to achieve bidirectional energy transfer.
Bipolar switching properties and electrical conduction mechanism in Sn:SiO sub( X )thin-film RRAM devices were investigated and discussed. To complete the resistive switching properties of the ...stannum doped into silicon oxide thin films, the RTA-treated Sn:SiO sub( X )thin-film RRAM devices were investigated and discussed. In addition, the improvement qualities and electrical switching properties of the RTA-treated Sn:SiO sub( X )thin-film RRAM devices were carried out XPS, FT-IR, and IV measurement. The ohmic conduction with metal-like behavior and hopping conduction dependent activation energy properties by the Arrhenius plot equation in LRS of the Sn:SiO sub( X )thin films was investigated. The activation energy and hopping distance for the RTA-treated thin films were found to be 0.018 eV and 1.1 nm, respectively. For the compatibility with the IC processes, the RTA treatment was a promising method for the Sn:SiO sub( X )thin-film RRAM nonvolatile memory applications.
This study proposes a method for a HfO
-based device to exhibit both resistive switching (RS) characteristics as resistive random access memory (RRAM) and selector characteristics by introducing ...vanadium (V) as the top electrode. This simple V/HfO
/TiN structure can demonstrate these two different properties depending on forming polarities. The RS mechanism is activated by a positive forming bias. In contrast, the selector property is induced by a negative forming bias. The material analyses firstly confirm the existence of V in the top electrode. Then the electrical measurements for the same V/HfO
/TiN structures but with different forming polarities were carried out to further investigate their DC sweeping characteristics to act as either a selector or RRAM device. Furthermore, reliability tests for both selector and RRAM devices were also conducted to confirm their switching stabilities. Finally, current fitting methods and temperature influence experiments were performed to investigate the carrier transport mechanisms. Finally, physical models were proposed to illustrate the selector property and RS mechanism for selector and RRAM devices, respectively. This simple device structure with its easy operating method accomplishes a significant advancement of devices combining both selector properties and RRAM for remarkable real applications in the near future.
Abstract
Background and Aim
Hepatocellular carcinoma (
HCC
) diagnosis could be made with one typical imaging study in a cirrhotic liver by the guideline of the
A
merican
A
ssociation for the
S
tudy ...of
L
iver
D
iseases (
AASLD
) in 2010. Patients with hepatitis
B
who may not have fully developed cirrhosis could be applied. We aim to retrospectively analyze and validate the diagnostic power of the 2010 guideline in an
HCC
endemic area (
T
aiwan).
Methods
From
J
anuary 2006 to
D
ecember 2010, a total of 648 patients with liver tumor post‐surgical resection were reviewed. The fibrotic scores were verified by
METAVIR
score 4. Among the 648 patients, 569 (87.8%) were
HCC
patients. Hepatitis
B
accounts for 54.5%, hepatitis
C
21.9%, hepatitis
B
+
C
2.8%, and non‐hepatitis
B
or
C
20.7% of patients. Two hundred eighty‐eight of 648 (44%) patients were with cirrhotic liver.
Results
The diagnostic sensitivity, specificity, positive predictive value (
PPV
), negative predictive value, and accuracy of the 2010
AASLD
guideline f are 99.1%, 36.7%, 91.9%, 85.3%, and 91.5%, respectively. Cirrhotic liver exhibited a higher
PPV
(
P
< 0.001) but lower specificity (
P
= 0.0479) than non‐cirrhotic liver. In both cirrhotic and non‐cirrhotic condition, no difference existed in patients with hepatitis
B
or hepatitis
C
(
P
> 0.05).
Conclusions
Similar sensitivity of
HCC
diagnosis existed between cirrhotic and non‐cirrhotic liver, and across different fibrotic stages. But cirrhotic liver exhibited a higher
PPV
. Hepatitis
B
or
C
has no decisive effect in
HCC
diagnosis.
Bipolar switching resistance behaviors of the Gd:SiO sub(2) resistive random access memory (RRAM) devices on indium tin oxide electrode by the low-temperature supercritical CO sub(2)-treated ...technology were investigated. For physical and electrical measurement results obtained, the improvement on oxygen qualities, properties of indium tin oxide electrode, and operation current of the Gd:SiO sub(2) RRAM devices were also observed. In addition, the initial metallic filament-forming model analyses and conduction transferred mechanism in switching resistance properties of the RRAM devices were verified and explained. Finally, the electrical reliability and retention properties of the Gd:SiO sub(2) RRAM devices for low-resistance state (LRS)/high-resistance state (HRS) in different switching cycles were also measured for applications in nonvolatile random memory devices.
To discuss the optoelectronic effect on resistive random access memory (RRAM) devices, the bipolar switching properties and electron-hole pair generation behavior in the transparent indium tin oxide ...(ITO) electrode of Gd:SiO sub(2) thin films under the ultraviolet ( lambda =400 nm) and red-light ( lambda =770 nm) illumination for high resistance state (HRS)/low resistance state (LRS) was observed and investigated. In dark environment, the Gd:SiO sub(2) RRAM devices exhibited the ohmic conduction mechanism for LRS, exhibited the Schottky emission conduction and Poole-Frankel conduction mechanism for HRS. For light illumination effect, the operation current of the Gd:SiO sub(2) RRAM devices for HRS/LRS was slightly increased. Finally, the electron-hole pair transport mechanism, switching conduction diagram, and energy band of the RRAM devices will be clearly demonstrated and explained.
A lower switching voltage of indiu-tin-oxide (ITO)-based resistance random access memory (RRAM) with an inserted SiO2 thin film was presented. The amplitude of switching voltage of device was below ...0.2 V whether measured by direct current or alternating current sweep operation. Notably, the observed reset voltage increased with temperature. To clarify the switching mechanism, conduction current fitting and switching voltage statistics were applied to explore the regular voltage variation dependent on temperature. In addition, a reaction model was proposed to explain the oxygen concentration gradient induced between the inserted SiO2 and ITO electrode on the ITO-based RRAM device.
Indiu-tin-oxide (ITO) is investigated as the top electrode material in HfO2-based resistive random access memory cells. Experimental results show that in contrast to a metal (Pt) electrode, an ITO ...electrode provides for self-limiting current flow during the forming and SET processes, so that no compliance limit is necessary. This provides for low-power consumption, high endurance (Formula Omitted cycles), and short SET/RESET transition times (Formula Omitted ns). We propose that this is because ITO is an oxygen-vacancy-rich material, providing bulk storage for oxygen ions rather than surface storage as a metal electrode.
PDF
