Oscillation and Photoresponse of High-Resistivity n-GaAs Diodes

1972 ◽  
Vol 50 (11) ◽  
pp. 1098-1105 ◽  
Author(s):  
A. B. Torrens ◽  
L. Young
Keyword(s):  
High Field ◽  
Room Temperature ◽  
Ohmic Contacts ◽  
Weak Field ◽  
Photoelectric Effect ◽  
High Resistivity ◽  
Initial Value ◽  
Small Current ◽  
A Value ◽  
Minority Carriers

Diodes of lengths 0.17 mm and 1 mm with ohmic contacts were made from n-type, ~ 16 Ωm-resistivity GaAs. The diode resistance varies with temperature as exp (−Δ*/kT), with Δ** 412 meV. Above a threshold voltage of 50 to 80 V, depending on the diode, a small current oscillation occurs in the short diodes, which can be explained by the periodic propagation of small high-field domains at a velocity of the order of 1 m/s at room temperature. Several features of the transient response of the diodes to pulses are consistent with the occurrence of weak field-enhanced trapping effects which could account for the formation of the high-field domains.The long diodes exhibit a novel photoelectric effect: if a diode is illuminated and is subjected to a high-voltage step, the current assumes initially a value proportional to the voltage. Then, in about 1 μs, it decays by as much as 92% of its initial value. All the characteristics of this effect can be explained in terms of accumulation of minority carriers (holes) at the cathode of the diode (which is blocking for holes).

Characterisation of Polycrystalline thin Films of Tellurium

1992 ◽  
Vol 283 ◽  
Author(s):  
A K Ray ◽  
C A Hogarth ◽  
R Swan
Keyword(s):  
High Field ◽  
Room Temperature ◽  
Energy Gap ◽  
High Vacuum ◽  
The Other ◽  
Corning Glass ◽  
A Value ◽  
Polycrystalline Thin Films ◽  
Tellurium Film ◽  
Limited Conduction

ABSTRACTStructural, electrical and optical characterisations were performed on tellurium film deposited under high vacuum conditions on ultrasonically cleaned Corning glass 7059 substrates. SEM and TEM studies reveal the polycrystalline nature of deposited tellurium films. At steady state high field conditions, space charge limited conduction is believed to have occurred due to the existence of a fast decaying density of trapping states in the energy gap. The DC conductivity is believed to exhibit a T-1/ law dependence below room temperature, giving a value of 2×10-l6eV/m3 for conduction states close to the Fermi level. From the power law dependence on frequency of AC conductivity, the barrier for bipolaron hopping is estimated to 0.33eV.Optical absorption in 9nm thick tellurium samples is due to direct transitions both allowed and forbidden producing two edges, the first one at 4eV and the other at about 0.5eV, respectively.

The Influence of Silicon Dopant and Processing on Thermoelectric Properties of B4C Ceramics

1998 ◽  
Vol 545 ◽  
Author(s):  
Ke-Feng Cai ◽  
Ce-Wen Nan ◽  
Xin-Min Min
Keyword(s):  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Figure Of Merit ◽  
Room Temperature ◽  
A Value ◽  
Si Doped

AbstractB4C ceramics doped with various content of Si (0 to 2.03 at%) are prepared via hot pressing. The composition and microstructure of the ceramics are characterized by means of XRD and EPMA. Their electrical conductivity and Seebeck coefficient of the samples are measured from room temperature up to 1500K. The electrical conductivity increases with temperature, and more rapidly after 1300K; the Seebeck coefficient of the ceramics also increases with temperature and rises to a value of about 320μVK−1. The value of the figure of merit of Si-doped B4C rises to about 4 × 10−4K−1 at 1500K.

Heat Transfer Analysis of Room-Temperature Finned-Tube Evaporator for Cryogenic Nitrogen

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
Shun Ching Lee ◽  
Tzu-Min Chen
Keyword(s):  
Heat Flux ◽  
Room Temperature ◽  
Integrated Model ◽  
Finned Tube ◽  
Heat Transfer Analysis ◽  
Outlet Temperature ◽  
Ambient Conditions ◽  
Governing Equations ◽  
Initial Value ◽  
Two Phase

Abstract The behavior of cryogenic nitrogen in a room-temperature evaporator six meters long is analyzed. Trapezoid fins are employed to enhance the heat flux supplied by the environment. The steady-state governing equations specified by the mixed parameters are derived from the conservations of momentum and energy. The initial value problem is solved by space integration. The fixed ambient conditions are confirmed by way of the meltback effect. An integrated model is utilized to analyze the convective effect of two-phase flow, which dominates the evaporation behavior. Another integrated model is employed to determine the total heat flux from the environment to the wet surface of the evaporator. The foundation of the formation of an ice layer surrounding the evaporator is presented. If the fin height is shorter than 0.5 m, the whole evaporator is surrounded by ice layer. If the fin height is longer than 0.5 m, the total pressure drop of nitrogen in the tube is negligible. The outlet temperature is always within the range between −12 °C and 16 °C for the evaporator with the fin height of 1.0 m. For the evaporator with dry surface, the nitrogen has the outlet temperature less than the ambient temperature at least by 5 °C.

Study on Schottky Diode Characteristics Improving by X-Ray Irradiation

2013 ◽  
Vol 717 ◽  
pp. 113-116
Author(s):  
Sani Klinsanit ◽  
Itsara Srithanachai ◽  
Surada Ueamanapong ◽  
Sunya Khunkhao ◽  
Budsara Nararug ◽  
...  
Keyword(s):  
Leakage Current ◽  
Schottky Diode ◽  
Room Temperature ◽  
The Other ◽  
Low Power Consumption ◽  
Initial Value ◽  
X Ray ◽  
Forward Current ◽  
Current Voltage ◽  
Current Voltage Characteristics

The effect of soft X-ray irradiation to the Schottky diode properties was analyzed in this paper. The built-in voltage, leakage current, and work function of Schottky diode were investigated. The current-voltage characteristics of the Schottky diode are measured at room temperature. After irradiation at 70 keV for 55 seconds the forward current and leakage current are increase slightly. On the other hand, the built-in voltage is decrease from the initial value about 0.12 V. Consequently, this method can cause the Schottky diode has low power consumption. The results show that soft X-ray can improve the characteristics of Schottky diode.

scholarly journals Observation of strong excitonic magneto-chiral anisotropy in twisted bilayer van der Waals crystals

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shoufeng Lan ◽  
Xiaoze Liu ◽  
Siqi Wang ◽  
Hanyu Zhu ◽  
Yawen Liu ◽  
...  
Keyword(s):  
Time Reversal ◽  
Room Temperature ◽  
Photochemical Reactions ◽  
Full Width ◽  
Half Maximum ◽  
A Value ◽  
Device Applications ◽  
Spectral Splitting ◽  
Iron Garnet ◽  
Spontaneous Magnetic Moment

AbstractThe interplay between chirality and magnetism generates a distinct physical process, the magneto-chiral effect, which enables one to develop functionalities that cannot be achieved solely by any of the two. Such a process is universal with the breaking of parity-inversion and time-reversal symmetry simultaneously. However, the magneto-chiral effect observed so far is weak when the matter responds to photons, electrons, or phonons. Here we report the first observation of strong magneto-chiral response to excitons in a twisted bilayer tungsten disulfide with the amplitude of excitonic magneto-chiral (ExMCh) anisotropy reaches a value of ~4%. We further found the ExMCh anisotropy features with a spectral splitting of ~7 nm, precisely the full-width at half maximum of the excitonic chirality spectrum. Without an externally applied strong magnetic field, the observed ExMCh effect with a spontaneous magnetic moment from the ferromagnetic substrate of thulium iron garnet at room temperature is favorable for device applications. The unique ExMCh processes provide a new pathway to actively control magneto-chiral applications in photochemical reactions, asymmetric synthesis, and drug delivery.

Doping and crystallization of amorphous SiGe films with an excimer (KrF) laser

1995 ◽  
Vol 10 (8) ◽  
pp. 1884-1888 ◽  
Author(s):  
S. Krishnan ◽  
M.I. Chaudhry ◽  
S.V. Babu
Keyword(s):  
Silicon Germanium ◽  
Room Temperature ◽  
Laser Pulses ◽  
Laser Exposure ◽  
Silicon Substrates ◽  
A Value ◽  
Crystal Film ◽  
Krf Laser ◽  
Amorphous Silicon Germanium

Amorphous silicon germanium (a-SiGe) films, deposited on silicon substrates at room temperature in a molecular beam epitaxy system, were transformed into a single-crystal film and doped with phosphorus by exposure to KrF laser pulses. Electron channeling patterns showed that laser exposure resulted in crystallization of the undoped a-SiGe films. The SiGe films were doped by laser irradiation, using a phosphorus spin-on-dopant. The sheet resistance of the doped films decreased with increasing numbers of pulses, reaching a value of about ∼ 5 × 104 ohms/□ after 15 pulses. I-V data from mesa-type n-SiGe/p-Si diode devices were used to determine the effect of laser processing on the quality of the SiGe films.

High field sensitivity at room temperature in p-n junction based bilayered manganite devices

2008 ◽  
Vol 92 (4) ◽  
pp. 043506 ◽  
Author(s):  
P. S. Vachhani ◽  
J. H. Markna ◽  
D. G. Kuberkar ◽  
R. J. Choudhary ◽  
D. M. Phase
Keyword(s):  
High Field ◽  
Room Temperature ◽  
Field Sensitivity

scholarly journals Preparation of Whey-Based Banana Beverage and its Quality Evaluation

2021 ◽  
Vol 5 (01) ◽  
pp. 60-66
Author(s):  
Kunjal Shrestha ◽  
Abhishek Dahal
Keyword(s):  
Sensory Analysis ◽  
Room Temperature ◽  
Storage Time ◽  
Value Added ◽  
Body Color ◽  
Overall Acceptability ◽  
A Value ◽  
Banana Juice ◽  
Nutritional Qualities ◽  
The One

A value-added functional beverage was formulated utilizing unprocessed whey with excellent nutritional qualities and bland flavors; along with banana juice and the required amount of sugar. Five different formulations were prepared with varying proportions of whey, banana juice, and sugar. Sensory analysis was carried out for all five formulations and based on statistical analysis the one which showed the highest value for body, color, flavor, taste, and overall acceptability was selected for further analysis (85% liquid whey and 15% banana juice). The shelf-life of the final product was observed for 30 days at room temperature (25±5°C) and refrigerated temperature (7±1ºC). A significant variation in body, color, flavor, taste, and overall acceptability were observed by varying the composition of whey and banana juice (p<0.05). The beverage was pasteurized at 82.5°C for 20 min and stored at normal (25±5°C) and refrigerated (7±1°C) for 30 days. The effects of storage time and temperature on physicochemical (TSS, pH, acidity) and microbial (TPC, yeast & mold count) properties were evaluated. Out of five formulations, the one selected via sensory analysis had TSS of 12.4°Bx, total solids 14.21%, 0.302% acidity, pH 5.72, 5.087% reducing sugar, 0.53% protein, 0.56% ash, 0.87% crude fiber, 184.43mg potassium (mg/100gm) and 0.912mg vitamin C in 100 ml. The prepared beverage was stored for 30 days under refrigerated and normal conditions, and changes in TSS, pH and acidity were observed: 12.413.3%, 5.72-5.214, 0.32-0.43%, and 12.4-13.8%, 5.72-4.64, 0.32-0.68% respectively. Overall analysis showed that the beverage prepared with 85% liquid whey and 15% banana juice could be stored for 30 days under refrigerated conditions without the addition of preservatives.

scholarly journals Inhibitive Effect of Costus afer Extracts on Mild Steel Corrosion in Acidic Medium

2016 ◽  
Vol 7 ◽  
pp. 60-67
Author(s):  
Lebe A. Nnanna ◽  
Wisdom O. John ◽  
Tochukwu E. Esihe ◽  
Kelechi C. Denkoro ◽  
Victor I. Okparaku ◽  
...  
Keyword(s):  
Mild Steel ◽  
Room Temperature ◽  
Inhibition Efficiency ◽  
Gravimetric Method ◽  
Steel Corrosion ◽  
Corrosion Process ◽  
Inhibition Effect ◽  
A Value ◽  
Mild Steel Corrosion ◽  
Costus Afer

Inhibition effect of Costusafer on mild steel in 0.5 M HCl was studied using gravimetric method at room temperature. It was found out that Costusafer inhibited the corrosion of mild steel in the acidic environment and that the efficiency of inhibition increased as the concentration of the inhibitor in the environment increased. The data was used to test different isotherms and it suited the Langmuir isotherm. A value of -15.995 kJmol-1 was gotten for the ∆Goads. This value showed that the extracts of Costusafer inhibited the corrosion process through physiosorption mechanism. The high value of inhibition efficiency of the extract as the concentration increased in rationalized in terms of the increase in herteroatoms, saponnins and tannins which are present in the extract.

MEMS-based LC tank with extended tuning range for low phase-noise VCO

2015 ◽  
Vol 9 (2) ◽  
pp. 249-258 ◽  
Author(s):  
Alessandro Cazzorla ◽  
Paola Farinelli ◽  
Laura Urbani ◽  
Fabrizio Cacciamani ◽  
Luca Pelliccia ◽  
...  
Keyword(s):  
Phase Noise ◽  
Quality Factor ◽  
Ohmic Contacts ◽  
Tuning Range ◽  
Design System ◽  
High Resistivity ◽  
Continuous Tuning ◽  
5 Ghz ◽  
Lc Tank ◽  
Low Phase Noise

This paper presents the modeling, manufacturing, and testing of a micro-electromechanical system (MEMS)-based LC tank resonator suitable for low phase-noise voltage-controlled oscillators (VCOs). The device is based on a variable MEMS varactor in series with an inductive coplanar waveguide line. Two additional parallel stubs controlled by two ohmic MEMS switches have been introduced in order to increase the resonator tunability. The device was fabricated using the FBK-irst MEMS process on high resistivity (HR) silicon substrate. Samples were manufactured with and without a 0-level quartz cap. The radio frequency characterization of the devices without 0-level cap has shown a continuous tuning range of 11.7% and a quality factor in the range of 33–38. The repeatability was also tested on four samples and the continuous tuning is 11.7 ± 2%. Experimental results on the device with a 0-level cap, show a frequency downshift of about 200 MHz and a degradation of the quality factor of about 20%. This is, most likely, due to the polymeric sealing ring as well as to a contamination of the ohmic contacts introduced by the capping procedure. A preliminary design of a MEMS-based VCO was performed using Advanced Design System and a hardwired prototype was fabricated on Surface Mount Technology on RO4350 laminate. The prototype was tested resulting in a resonance frequency of 5 GHz with a phase noise of −105 and −126 dBc at 100 KHz and 1 MHz, respectively, and a measured output power of −1 dBm.

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