Investigations of Oxidation Dependence on Type of Porous Silicon Near Room Temperature by Isothermal Microcalorimeter

1997 ◽  
Vol 485 ◽  
Author(s):  
J. Salonen ◽  
V-P. Lehto ◽  
E. Laine
Keyword(s):  
Activation Energy ◽  
Porous Silicon ◽  
Room Temperature ◽  
Activity Monitoring ◽  
Thermal Activity ◽  
Autocatalytic Reactions ◽  
The Difference ◽  
P Type ◽  
Isothermal Microcalorimeter

AbstractOxidation of porous silicon has been studied using thermal activity monitoring, i.e. isothermal microcalorimeter. It was found that, at room temperature (25 °C) the micro-calorimetric signal from the oxidation of the p+-type porous silicon (PS) reduces exponentially, while in the case of n-type PS, the signal starts to increase slowly, reaching its highest value after some hours. This kind of behaviour is typical of autocatalytic reactions. To clarify the origin of the difference, we varied the preparation parameters of the porous silicon. We determined the activation energy from the measurements near the room temperature (25–70 °C). The results of this research have been compared with the previous observations and the possible origin of the difference has been discussed.

scholarly journals Electrical properties of pure NiO and NiO:Au thin films prepared by using pulsed laser deposition

2019 ◽  
Vol 14 (29) ◽  
pp. 37-43 ◽  
Author(s):  
Raied K. Jamal
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Electrical Properties ◽  
Transport Mechanism ◽  
Room Temperature ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Concentration Increase ◽  
Annealing Temperatures ◽  
P Type

The electrical properties of pure NiO and NiO:Au Films which aredeposited on glass substrate with various dopant concentrations(1wt.%, 2wt%, 3wt.% and 4wt.%) at room temperature 450 Coannealing temperature will be presented. The results of the hall effectshowed that all the films were p-type. The Hall mobility decreaseswhile both carrier concentration and conductivity increases with theincreasing of annealing temperatures and doping percentage, Thus,indicating the behavior of semiconductor, and also the D.Cconductivity from which the activation energy decrease with thedoping concentration increase and transport mechanism of the chargecarriers can be estimated.

scholarly journals Substitution Versus Full-Heusler Segregation in TiCoSb

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 935 ◽  
Author(s):  
Maryana Asaad ◽  
Jim Buckman ◽  
Jan-Willem Bos
Keyword(s):  
Powder Metallurgy ◽  
Power Factor ◽  
Thermoelectric Materials ◽  
Room Temperature ◽  
The Difference ◽  
P Type ◽  
Full Heusler ◽  
Thermal Conductivities

Half-Heuslers (HHs) are promising thermoelectric materials with great compositional flexibility. Here, we extend work on the p-type doping of TiCoSb using abundant elements. Ti0.7V0.3Co0.85Fe0.15Sb0.7Sn0.3 samples with nominal 17.85 p-type electron count were investigated. Samples prepared using powder metallurgy have negative Seebeck values, S ≤ −120 µV K−1, while arc-melted compositions are compensated semiconductors with S = −45 to +30 µV K−1. The difference in thermoelectric response is caused by variations in the degree of segregation of V(Co0.6Fe0.4)2Sn full-Heusler and Sn phases, which selectively absorb V, Fe, and Sn. The segregated microstructure leads to reduced lattice thermal conductivities, κlat = 4.5−7 W m−1 K−1 near room temperature. The largest power factor, S2/ρ = 0.4 mW m−1 K−2 and ZT = 0.06, is observed for the n-type samples at 800 K. This works extends knowledge regarding suitable p-type dopants for TiCoSb.

scholarly journals The Internal Friction of Single Crystals, Bicrystals and Polycrystals of Pure Magnesium

2015 ◽  
Vol 60 (1) ◽  
pp. 371-375 ◽  
Author(s):  
W.B. Jiang ◽  
Q.P. Kong ◽  
L.B. Magalas ◽  
Q.F. Fang
Keyword(s):  
Activation Energy ◽  
Internal Friction ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Room Temperature ◽  
Internal Friction Peak ◽  
Self Diffusion ◽  
Boundary Relaxation ◽  
The Difference

Abstract The internal friction of magnesium single crystals, bicrystals and polycrystals has been studied between room temperature and 450°C. There is no internal friction peak in the single crystals, but a prominent relaxation peak appears at around 160°C in polycrystals. The activation energy of the peak is 1.0 eV, which is consistent with the grain boundary self-diffusion energy of Mg. Therefore, the peak in polycrystals can be attributed to grain boundary relaxation. For the three studied bicrystals, the grain boundary peak temperatures and activation energies are higher than that of polycrystals, while the peak heights are much lower. The difference between the internal friction peaks in bicrystals and polycrystals is possibly caused by the difference in the concentrations of segregated impurities in grain boundaries.

Electrical and Magnetic Properties of CuEu2W2O10 and Cu3Eu2W4O18

2012 ◽  
Vol 194 ◽  
pp. 104-107 ◽  
Author(s):  
Piotr Urbanowicz ◽  
Elzbieta Tomaszewicz ◽  
Tadeusz Groń ◽  
Henryk Duda ◽  
Slawomir Mazur ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Activation Energy ◽  
Magnetic Properties ◽  
Room Temperature ◽  
Linear Temperature Dependence ◽  
Linear Temperature ◽  
Weak Response ◽  
Thermally Activated ◽  
Electrical And Magnetic Properties ◽  
P Type

Magnetic susceptibility measurements showed both a weak response to magnetic field and a lack of the Curie-Weiss region for CuEu2W2O10and Cu3Eu2W4O18tungstates characteristic for the multiplet widths comparable to thermal energy. Magnetization measurements displayed the linear temperature dependence with the lower magnetic moment for Cu3Eu2W4O18in comparison with CuEu2W2O10, indicating that the effect of the electric charges associated with the surrounding ligands can change the multiplet width of individual states. It is affecting the electrical properties of examined tungstates which reveal the insulating state and low relative permittivity εr ~ 29 in case of CuEu2W2O10and the thermally activated p-type electrical conduction for Cu3Eu2W4O18with the activation energy of 1.11 eV and the large value of εr ~ 217 above the room temperature.

Formation of a Low Reflective Surface on Silicon Solar Cells by Chemical Treatment Using Ag-Assisted Electroless Etching

2012 ◽  
Vol 512-515 ◽  
pp. 43-46
Author(s):  
Guo Feng Ma ◽  
Hong Ling Zhang ◽  
Xue Fei Yang
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
Silicon Solar Cells ◽  
Mixed Solution ◽  
Etching Solution ◽  
Electroless Etching ◽  
Ag Particle ◽  
P Type

The Ag-assisted electroless etching of p-type silicon substrate in HF/H2O2solution at room temperature was investigated. The porous silicon layer was formed in a mixed solution of H2O2and HF by using screen-printed Ag front electrodes as the catalyst. And influence of the different concentration etching solution (HF and AgNO3) on the porous silicon layer was study by scanning electron microscopy (SEM). Through investigation of the track of catalyst particles, it was shown that Ag really catalyses the etching of silicon underneath Ag particle.

scholarly journals Room-Temperature H2 Gas Sensing Characterization of Graphene-Doped Porous Silicon via a Facile Solution Dropping Method

2017 ◽  
Author(s):  
Nu Si A Eom ◽  
Hong-Baek Cho ◽  
Yoseb Song ◽  
Woojin Lee ◽  
Tohru Sekino ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Gas Sensor ◽  
Room Temperature ◽  
Gas Sensing ◽  
Electrochemical Etching ◽  
Sensor Material ◽  
Sensing Mechanism ◽  
Si Substrates ◽  
H2 Sensor ◽  
P Type

In this study, a graphene-doped porous silicon (G-doped/p-Si) substrate for low ppm H2 gas detection by an inexpensive synthesis route was proposed as a potential noble graphene-based gas sensor material and to understand the sensing mechanism. The G-doped/p-Si gas sensor was synthesized by a simple capillary force-assisted solution dropping method on p-Si substrates, whose porosity was generated through an electrochemical etching process. G-doped/p-Si was fabricated with various graphene concentrations and exploited as a H2 sensor operated at room temperature. The sensing mechanism of the sensor with/without graphene decoration on p-Si was proposed to elucidate the synergetic gas sensing effect generated from the interface between the graphene and p-type silicon.

High-Power High-Temperature Heterobipolar TransistorWith Gallium Nitride Emitter

1996 ◽  
Vol 1 ◽  
Author(s):  
J. I. Pankove ◽  
M. Leksono ◽  
S. S. Chang ◽  
C. Walker ◽  
B. Van Zeghbroeck
Keyword(s):  
Activation Energy ◽  
Gallium Nitride ◽  
High Power ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Arrhenius Plot ◽  
Wide Bandgap ◽  
Current Gain ◽  
Energy Gaps ◽  
The Difference

A new heterobipolar transistor was made with the wide bandgap semicon-ductors gallium nitride (GaN) and silicon carbide (SiC). The heterojunction allows high injection efficiency, even at elevated temperatures. A record current gain of ten million was obtained at room temperature, decreasing to 100 at 535°C. An Arrhenius plot of current gain vs 1/T yields an activation energy of 0.43 eV that corresponds to the valence band barrier blocking the escape of holes from the base to the emitter. This activation energy is approximately equal to the difference of energy gaps between emitter and base. This Transistor can operate at high power without cooling. A power density of 30 KW/cm2 was sustained.

Luminescence of Rare Earth Doped Porous Silicon

1996 ◽  
Vol 422 ◽  
Author(s):  
T. Kimura ◽  
I. Hosokawa ◽  
Y. Nishida ◽  
T. Dejima ◽  
R. Saito ◽  
...  
Keyword(s):  
Rare Earth ◽  
Porous Silicon ◽  
Room Temperature ◽  
Luminescence Decay ◽  
Rare Earth Ions ◽  
Energy Transfer Mechanism ◽  
Free Atmosphere ◽  
Optical Activation ◽  
P Type ◽  
Rare Earth Doped

AbstractPhotoluminescence characteristics of porous silicon layers (PSLs) doped with Er or Yb ions are studied. 10μm thick PSLs with a luminescence centered at ∼ 0.8μm are formed by anodic etching of p-type silicon wafers of several Ω-cm resistivity. Rare-earth ions are electrochemically incorporated into PSLs. The Er3+-related luminescence at 1.54μm as well as the Yb3+-related luminescence at 1.0μm is observed at room temperature after annealing at high temperatures (>900°C). The Er-related luminescence is enhanced after annealing in O2, whereas the Yb3+-related luminescence needs oxygen-free atmosphere (H2) for the optical activation. The luminescence decay time of the rare earth ions as well as the host PSLs is measured and the energy transfer mechanism is discussed.

Effect of Cu doping on the electrical Properties of ZnTe by Vacuum Thermal Evaporation

2018 ◽  
Vol 31 (3) ◽  
pp. 20
Author(s):  
Sarmad M. M. Ali ◽  
Alia A.A. Shehab ◽  
Samir A. Maki
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Hall Effect ◽  
Carrier Concentration ◽  
Hall Mobility ◽  
Cu Doping ◽  
Before And After ◽  
Hall Effect Measurements ◽  
Evaporation Technique ◽  
P Type

In this study, the ZnTe thin films were deposited on a glass substrate at a thickness of 400nm using vacuum evaporation technique (2×10-5mbar) at RT. Electrical conductivity and Hall effect measurements have been investigated as a function of variation of the doping ratios (3,5,7%) of the Cu element on the thin ZnTe films. The temperature range of (25-200°C) is to record the electrical conductivity values. The results of the films have two types of transport mechanisms of free carriers with two values of activation energy (Ea1, Ea2), expect 3% Cu. The activation energy (Ea1) increased from 29meV to 157meV before and after doping (Cu at 5%) respectively. The results of Hall effect measurements of ZnTe , ZnTe:Cu films show that all films were (p-type), the carrier concentration (1.1×1020 m-3) , Hall mobility (0.464m2/V.s) for pure ZnTe film, increases the carrier concentration (6.3×1021m-3) Hall mobility (2m2/V.s) for doping (Cu at 3%) film, but  decreases by increasing Cu concentration.

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