Resistive switching properties of nanoscale zirconium dioxide (ZrO
2
) thin film deposited by plasma-enhanced atomic layer deposition (PE-ALD) have been investigated. A resistive memory device has ...been formed with a 10-nm-thick ZrO
2
film as an active switching layer sandwiched between an aluminum top electrode and a silver bottom electrode. Bipolar resistive switching characteristics were demonstrated by current–voltage measurements with a read memory window of 6.6 V, an ON/OFF current ratio of nearly 10
5
, and a retention time of 10
4
s. Current conduction at low resistance states follows Ohm’s law while at a high-resistance state governed by space charge limited conduction. These indicate that the switching mechanism is attributed to filamentary conduction. A SPICE model was applied to model the device, with simulation measurement data in good agreement. This study proves the potential applications of PE-ALD ZrO
2
for non-volatile resistive random access memories.
Metal-organic decomposed lanthanum cerium oxide (La
x
Ce
y
O
z
) film had been spin-coated on n-type Si substrate. Effects of post-deposition annealing temperature and time on the ...metal-oxide-semiconductor (MOS) properties of the film were studied. As temperature increased from 400 to 1000°C for 15 minutes dwell time, La
x
Ce
y
O
z
demonstrated a decrease in interface trap density (
D
it
) and total interface trap density (
D
total
), which were related to the formation of SiO
x
/silicates interfacial layer (IL). The lowest leakage current density and highest dielectric breakdown voltage (
V
B
) was obtained in 1000°C-annealed sample. When longer annealing times (30–120 minutes) were studied on the 1000°C-annealed sample, the sample annealed at 1000°C for 120 min showed the best MOS characteristics with
V
B
of 30 V. Reasons contributing to such observation were discussed.
In recent years, because of stringent needs in the fabrication of silicon carbide (SiC) power devices, laser annealing has been introduced to achieve local ohmic contact. In this paper, the laser ...annealing research for the ohmic contact process of SiC power devices is reviewed, which is mainly divided into four aspects: laser process mechanism, ohmic contact electrode materials, and substrate materials. The effect of laser parameters on ohmic contact and the annealing process on SiC diode devices is also reviewed. Progress of other substrate materials, namely 6H-SiC and semi-insulating 4H-SiC-based devices with laser annealed ohmic contacts, is also briefly discussed, in which formation of semi-insulating SiC ohmic contacts is derived from laser irradiation at the interface to produce 3C-SiC. Some experiment results have been shown in the passage, such as XRD, SEM, TEM, etc. In the review, it points out that the direction of application and development of the laser annealing process for improving the ohmic contact of SiC power devices is highly encouraging.
The band alignment of ZrO
2
/interfacial layer/Si structure fabricated by simultaneous oxidation and nitridation of sputtered Zr on Si in N
2
O at 700°C for different durations has been established ...by using X-ray photoelectron spectroscopy. Valence band offset of ZrO
2
/Si was found to be 4.75 eV, while the highest corresponding conduction offset of ZrO
2
/interfacial layer was found to be 3.40 eV; owing to the combination of relatively larger bandgaps, it enhanced electrical breakdown field to 13.6 MV/cm at 10
-6
A/cm
2
.
Sm2O3 gate dielectric on Si substrate WEN CHIAO CHIN; KUAN YEW CHEONG; HASSAN, Zainuriah
Materials science in semiconductor processing,
12/2010, Letnik:
13, Številka:
5-6
Journal Article
Recenzirano
High dielectric constant ( Kappa ) materials have become a necessity for down scaling of metal-oxide-semiconductor (MOS) based devices. Rare-earth oxides have been studied as alternative dielectric ...material to replace SiO2 gate for future Si-based technology due to their excellent dielectric properties and thermodynamic stability with Si. This paper reviews reasons behind the use of rare-earth oxides as alternative high- Kappa dielectric materials and their requirements. Of these rare-earth oxides, Sm2O3 is one of the potential candidates that capture the attention of researchers owing to its intrinsic properties. These properties have been reviewed in comparison with the properties of other rare-earth oxides. Various deposition methods of Sm2O3 thin films on Si are also described, compared, and related to their physical and electrical properties. Based on the outcome of this review, Sm2O3 thin film has a huge potential to be the alternative dielectric for future MOS based devices when the listed challenges are resolved.
This paper presents the effects of postdeposition annealing temperatures (400, 600, 800, and 1000°C) in oxygen ambient on the metal-organic decomposed CeO 2 films spin coated on an n-type GaN ...substrate. The compositions, structures, and morphologies of these samples are revealed by X-ray diffraction (XRD), field-emission scanning electron microscopy, and an atomic force microscope. XRD analysis discloses the presence of CeO 2 films, α-Ce 2 O 3 , and an interfacial layer of β-Ga 2 O 3 . The formation of α-Ce 2 O 3 is due to the phase transformation of CeO 2 , whereas the β-Ga 2 O 3 interfacial layer is formed due to the inward diffusion of the released oxygen from CeO 2 reacting with decomposed GaN. These characterization results are then correlated with the metal-oxide-semiconductor characteristics of the CeO 2 gate annealed at different temperatures. It has been demonstrated that oxide annealed at 1000°C shows the lowest semiconductor-oxide interface-trap density, effective oxide charge, and the highest dielectric breakdown field.
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► Hierarchically meso–macroporous t-ZrO2 thin films were prepared by spin-coating via Pluronic P123 templated sol–gel route. ► Increasing rotation speed during spin-coating decreased ...surface roughness and oxide thickness. ► By coating second layer of ZrO2 film, surface roughness of respective film decreased slightly and the thickness increases. ► Mesostructures of ZrO2 film are disordered worm-like mesopores coexisted with macropores.
Hierarchically meso–macroporous tetragonal ZrO2 (t-ZrO2) thin films with tunable thickness were prepared by spin-coating method via Pluronic P123 templated sol–gel route. This hierarchically porous ZrO2 was characterized by field-emission scanning electron microscope, atomic force microscope, nitrogen adsorption–desorption isotherm, X-ray diffraction, and ultraviolet–visible spectrometer. Effects of rotation speed and by coating another layer of sol on the first layer during spin-coating on the thickness and mesoporous structure of ZrO2 thin films formed were investigated. The meso–macroporous ZrO2 film coated on a glass substrate possessed an average transmittance higher than 80% in the visible range. It was suggested that the structure of Pluronic P123 was changed as concentration of deposited sol varied over time, which led to the formation of worm-like mesospores coexisted with macropores and rod-like ZrO2 framework. Formation of cracks on ZrO2 thin films was initiated by the structure of meso–macropores and shrinkage of respective films.
•Hydrogen bonding favors the long-range self-assembly leading to an entangled network structure.•The non-liquid crystalline gelator can be converted into liquid crystalline organogel.•The organogel ...exhibited monotropic nematic and smectic A phases.•The trans-cis isomerization of the azobenzene moiety disrupts the entanglement of gel fibers of self-assembly resulting in gel–sol transition.•The organogel is capable of the thermal and photo induced transition from gel–sol and vice versa.
Azobenzene based photoresponsive gelator, 1,2-bis4-(4-(10-decyloxy)phenylazo)-benzoylhydrazine showing selective gelation in alcoholic solvent is described. Whilst their thermodynamic behaviors are investigated by polarized optical microscopy and differential scanning calorimetry, the related layer arrangement is measured by X-ray diffraction techniques in which the organogel shows monotropic liquid crystalline phase. Present work shows that the non-liquid crystalline gelator can be converted into liquid crystalline organogel in the presence of alcoholic solvent in which the trans-cis isomerization of the azobenzene moiety disrupts the entanglement of gel fibers of self-assembly resulting in gel–sol transition. The present result also shows that the organogel is capable of the thermal and photo induced transition from gel–sol and vice versa.
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