THEORETICAL STUDIES ON PIEZORESISTIVE EFFECT OF P-TYPE DIAMOND FILMS

2002 ◽  
Vol 16 (06n07) ◽  
pp. 916-921
Author(s):  
W. L. WANG ◽  
K. J. LIAO ◽  
C. Z. CAI ◽  
C. Y. KONG ◽  
S. X. WANG
Keyword(s):  
Diamond Films ◽  
Uniaxial Stress ◽  
Theoretical Description ◽  
Boltzmann Transport ◽  
Piezoresistive Effect ◽  
Relaxation Time Approximation ◽  
Hole Band ◽  
Mixed Scattering ◽  
P Type ◽  
Good Agreement

In this paper, based on the Fuchs and Sondheimer theory and valence band split-off model, a theoretical description of the piezoresistive effect in P-type heteroepitaxial diamond films was presented by solving the Boltzmann transport equation in the relaxation time approximation, in which a mixed scattering by lattice vibration, ionized impurities and surface was considered. A calculating expression of the piezoresistive effect has been developed in a parallel connection resistance model for the light-hole band, the heavy-hole band and the split-off band. The calculating results were in good agreement with the experimental data, indicating that the prezoresistive effect in diamond films was mainly ascribed to the hole band split-off under a uniaxial stress.

scholarly journals Absolute Pressure Dependence of the Second Ionization Level of EL2 in GaAs

1989 ◽  
Vol 163 ◽  
Author(s):  
D.E. Bliss ◽  
W. Walukiewicz ◽  
D.D. Nolte ◽  
E.E. Haller
Keyword(s):  
Pressure Dependence ◽  
Emission Rate ◽  
Uniaxial Stress ◽  
Absolute Pressure ◽  
Pressure Derivative ◽  
Effective Masses ◽  
The Difference ◽  
P Type ◽  
Derivatives Of ◽  
Good Agreement

AbstractWe report the results of DLTS experiments under uniaxial stress on the second ionization level of EL2(++/+) in p-type GaAs. We measured the shift in the hole emission rate as a function of stress applied in the [100] and [110] directions. By modeling the valence band with two independently displacing bands and appropriately derived effective masses, we obtain a small absolute hydrostatic pressure derivative for the defect, 39 ±15 meV GPa-1. The shear contribution is negligible. This result is very different than for the first ionization level, EL2(+/o) with a emission energy pressure derivative of 90 ±15 meV GPa-1. The difference can be accounted for by the pressure dependence of the electron capture barrier of EL2(+/o), 49 ±15meV GPa-1. The absolute pressure derivatives of the two levels are then comparable and in good agreement with simple theory for Ga site point defects.

Piezoresistive effect in p-type polycrystalline diamond films

1999 ◽  
Vol 42 (7) ◽  
pp. 769-777
Author(s):  
Liang Fang ◽  
Wanlu Wang ◽  
Peidao Ding ◽  
Kejun Liao ◽  
Jian Wang
Keyword(s):  
Diamond Films ◽  
Polycrystalline Diamond ◽  
Piezoresistive Effect ◽  
P Type

scholarly journals Optimal Carrier Concentration for High Thermoelectric Performance of Lead Substituted Bismuth Telluride in p-Type Doping

2018 ◽  
Vol 28 (2) ◽  
pp. 169
Author(s):  
Van Quang Tran
Keyword(s):  
Carrier Concentration ◽  
Thermoelectric Materials ◽  
Density Functional ◽  
Room Temperature ◽  
Density Functional Theory Calculation ◽  
Binary Compound ◽  
Thermoelectric Performance ◽  
Boltzmann Transport ◽  
Relaxation Time Approximation ◽  
P Type

Bi\(_{2}\)Te\(_{3}\) and its alloys are the well-known state-of-the-art thermoelectric materials operating at around room temperature. With lead substituted, the newly formed quasi-binary compound PbBi\(_{4}\)Te\(_{7}\), shows relatively high electrical conductivity and Seebeck coefficient. In this report, we employed the solution of the Boltzmann Transport Equation in a constant relaxation-time approximation within a first-principles density-functional-theory calculation to explore the role of the electronic thermal conductivity, \(\kappa _{e}\), on the thermoelectric performance of the compound with p-type doping. Results show that \(\kappa _{e}\) increases drastically with the increases of both temperature and carrier concentration. Even the power factor has been found to be markedly improved with the increase of the carrier concentration, a rapid increase of \(\kappa _{e}\) emerges as a big hindrance to improve the dimensionless figure of merit, ZT, of the compound. This is responsible for the limit of ZT. The larger ZT is found in low temperatures and carrier concentrations. The highest ZT of about 0.48 occurs at 223 K and at the carrier concentration of \(6\times 10^{17}\)cm\(^{ - 3}\). At room temperature the maximum ZT is slightly smaller. We demonstrated that at a particular temperature to maximize the thermoelectric performance of the compound, the carrier concentration must be optimized. Results show that the compound with p-type doping is a promising thermoelectric materials operating at around room temperature.

A compact UWB antenna with triple band notch reconfigurability

2020 ◽  
pp. 1-7
Author(s):  
Lei Li ◽  
Jingchang Nan ◽  
Jing Liu ◽  
Chengjian Tao
Keyword(s):  
Coplanar Waveguide ◽  
Ring Resonators ◽  
Uwb Antenna ◽  
Split Ring ◽  
X Band ◽  
Compact Size ◽  
Nested Structure ◽  
P Type ◽  
Good Agreement ◽  
Triple Band

Abstract A compact ultrawideband (UWB) antenna with reconfigurable triple band notch characteristics is proposed in this paper. The antenna consists of a coplanar waveguide-fed top-cut circular-shaped radiator with two etched C-shaped slots, a pair of split-ring resonators (SRRs) on the backside and four p-type intrinsic n-type (PIN) diodes integrated in the slots and SRRs. By controlling the current distribution in the slots and SRRs, the antenna can realize eight band notch states with independent switch ability, which allows UWB to coexist with 5G (3.3–4.4 GHz)/WiMAX (3.3–3.6 GHz), WLAN (5.15–5.825 GHz), and X-band (7.9–8.4 GHz) bands without interference. By utilizing a nested structure of C-shaped slots and SRRs on the backside, a compact size of 18 × 19.5 mm2 is achieved along with multimode triple band notch reconfigurability. The antenna covers a bandwidth of 3.1–10.6 GHz. A prototype is fabricated and tested. The simulated and experimental results are in good agreement.

scholarly journals Band degeneracy enhanced thermoelectric performance in layered oxyselenides by first-principles calculations

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Ning Wang ◽  
Menglu Li ◽  
Haiyan Xiao ◽  
Zhibin Gao ◽  
Zijiang Liu ◽  
...  
Keyword(s):  
Density Functional ◽  
Transport Theory ◽  
Relaxation Times ◽  
Wide Band ◽  
Type Systems ◽  
Model Systems ◽  
Boltzmann Transport ◽  
Seebeck Coefficients ◽  
Boltzmann Transport Theory ◽  
P Type

AbstractBand degeneracy is effective in optimizing the power factors of thermoelectric (TE) materials by enhancing the Seebeck coefficients. In this study, we demonstrate this effect in model systems of layered oxyselenide family by the density functional theory (DFT) combined with semi-classical Boltzmann transport theory. TE transport performance of layered LaCuOSe and BiCuOSe are fully compared. The results show that due to the larger electrical conductivities caused by longer electron relaxation times, the n-type systems show better TE performance than p-type systems for both LaCuOSe and BiCuOSe. Besides, the conduction band degeneracy of LaCuOSe leads to a larger Seebeck coefficient and a higher optimal carrier concentration than n-type BiCuOSe, and thus a higher power factor. The optimal figure of merit (ZT) value of 1.46 for n-type LaCuOSe is 22% larger than that of 1.2 for n-type BiCuOSe. This study highlights the potential of wide band gap material LaCuOSe for highly efficient TE applications, and demonstrates that inducing band degeneracy by cations substitution is an effective way to enhance the TE performance of layered oxyselenides.

scholarly journals Study on the Stability of the Electrical Connection of High-Temperature Pressure Sensor Based on the Piezoresistive Effect of P-Type SiC

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 216
Author(s):  
Yongwei Li ◽  
Ting Liang ◽  
Cheng Lei ◽  
Qiang Li ◽  
Zhiqiang Li ◽  
...  
Keyword(s):  
High Temperature ◽  
Pressure Sensor ◽  
Pressure Sensors ◽  
Extreme Environment ◽  
Maximum Temperature ◽  
Piezoresistive Effect ◽  
Electrical Connection ◽  
Contact Stability ◽  
The Stability ◽  
P Type

In this study, a preparation method for the high-temperature pressure sensor based on the piezoresistive effect of p-type SiC is presented. The varistor with a positive trapezoidal shape was designed and etched innovatively to improve the contact stability between the metal and SiC varistor. Additionally, the excellent ohmic contact was formed by annealing at 950 °C between Ni/Al/Ni/Au and p-type SiC with a doping concentration of 1018cm−3. The aging sensor was tested for varistors in the air of 25 °C–600 °C. The resistance value of the varistors initially decreased and then increased with the increase of temperature and reached the minimum at ~450 °C. It could be calculated that the varistors at ~100 °C exhibited the maximum temperature coefficient of resistance (TCR) of ~−0.35%/°C. The above results indicated that the sensor had a stable electrical connection in the air environment of ≤600 °C. Finally, the encapsulated sensor was subjected to pressure/depressure tests at room temperature. The test results revealed that the sensor output sensitivity was approximately 1.09 mV/V/bar, which is better than other SiC pressure sensors. This study has a great significance for the test of mechanical parameters under the extreme environment of 600 °C.

scholarly journals DEPOSITION CARBON NANOSTRUCTURES BY SURFATRON GENERATED DISCHARGE

2014 ◽  
Vol 54 (6) ◽  
pp. 389-393
Author(s):  
Marina Davydova ◽  
Jiri Smid ◽  
Zdenek Hubicka ◽  
Alexander Kromka
Keyword(s):  
Carbon Nanostructures ◽  
Treatment Time ◽  
Diamond Films ◽  
Diamond Surface ◽  
Process Time ◽  
Low Temperature Plasma ◽  
Temperature Plasma ◽  
Gas Concentration ◽  
P Type ◽  
Wave Discharge

Carbon nanostructures were deposited by surface wave discharge using various Ar/CH<sub>4</sub>/ CO<sub>2</sub> gas mixture ratios. The morphology was controlled by adjusting of gas concentration and was investigated by scanning electron microscopy (SEM). Also, the influence of the low temperature plasma treatment and process time on the wettability of the diamond films has been studied. The results indicate that for hydrogen termination of diamond surface indicate that the temperature as low as 400°C and treatment time of 15 min is sufficient to attain the p-type surface conductivity of diamond.

Quantum-Confined Optical Interband Transitions in 5-Doped Doping Superlattices

1989 ◽  
Vol 145 ◽  
Author(s):  
E. F. Schubert ◽  
T. D. Harris ◽  
J. E. Cunningham
Keyword(s):  
Emission Spectra ◽  
Doping Profile ◽  
Luminescence Spectra ◽  
Interband Transitions ◽  
Doping Technique ◽  
Quantum Confined ◽  
P Type ◽  
First Time ◽  
Experimental Absorption ◽  
Good Agreement

AbstractOptical absorption and photoluminescence experiments are performed on GaAs doping superlattices, which have a δ-function-like doping profile of alternating n-type and p-type dopant sheets. Absorption and emission spectra reveal for the first time the clear signature of quantum-confined interband transitions. The peaks of the experimental absorption and luminescence spectra are assigned to calculated energies of quantum-confined transitions with very good agreement. It is shown that the employment of the δ-doping technique results in improved optical properties of doping superlattices.

Evidence of a single-q incommensurate phase in quartz by synchrotron X-ray diffraction

1988 ◽  
Vol 21 (1) ◽  
pp. 72-74 ◽  
Author(s):  
A. Zarka ◽  
B. Capelle ◽  
M. Petit ◽  
G. Dolino ◽  
P. Bastie ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Uniaxial Stress ◽  
Incommensurate Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Good Agreement ◽  
Ray Scattering

X-ray scattering is used to demonstrate the existence in quartz of an incommensurate phase with a single modulation when a uniaxial stress is applied in the X Y plane. Good agreement with earlier neutron scattering experiments is found.

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