Dielectric Spectroscopy Study Of Znse Grown By Physical Vapor Transport

1997 ◽  
Vol 487 ◽  
Author(s):  
Julie Kokan ◽  
Rosario Gerhardt ◽  
Ching-Hua Su
Keyword(s):  
Heat Treatment ◽  
Dielectric Properties ◽  
Dielectric Spectroscopy ◽  
Wide Band ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Spectroscopy Study ◽  
Wide Band Gap ◽  
Heat Treated ◽  
Semiconducting Properties

AbstractZnSe, although generally thought of as a wide band gap semiconductor, is insulating in the as-grown state. It is only after heat treatment in a zinc rich atmosphere that semiconducting properties are observed Therefore, dielectric spectroscopy is an appropriate tool to study the electrical properties of as grown ZnSe. The dielectric properties of large-grained samples of ZnSe grown by physical vapor transport were measured as a function of frequency. Differences can be seen in the dielectric properties of samples grown under different conditions (such as the effect of a seed and the orientation of the gravity field during growth). The spectra of heat treated samples were also acquired and were found to exhibit significant deviations from those of the as grown crystals.

EPR Study of the Role of Hydrogen in the Defect Formation Upon Heat Treatment of Oxidized SiC

1998 ◽  
Vol 513 ◽  
Author(s):  
P. J. Macfarlane ◽  
M. E. Zvanut
Keyword(s):  
Heat Treatment ◽  
Defect Formation ◽  
Wide Band ◽  
Oxide Semiconductor ◽  
Wide Band Gap ◽  
Paramagnetic Resonance ◽  
Hydrogen Incorporation ◽  
Si Substrates ◽  
Mos Devices ◽  
Dry Heat Treatment

ABSTRACTFor the past several years hydrogen incorporation in metal oxide semiconductor (MOS) devices has been of interest because studies have shown that vacuum annealing of oxidized Si substrates desorbs hydrogen, revealing interfacial defects. Today, in applications that require higher power and/or temperature, Si will likely be replaced with a wide-band-gap semiconductor. For MOS devices, SiC is a leading contender because it can be thermally oxidized to form a SiO2 insulating layer similar to Si. However, the SiC/SiO2 structure potentially contains hydrogen sensitive centers similar to those found in Si/SiO2 structures. Using electron paramagnetic resonance (EPR), we have observed a center 1.8 G wide peak-to-peak at g=2.0026. The center is generated in oxidized SiC that has received a 900° C dry, N2 or O2, post oxidation heat-treatment in which moisture is measured to be less than 1 ppm. Annealing at 900° C in standard Ar containing at least 50 ppm H2O decreases the center's concentration by two orders of magnitude. By comparing results from our study to studies of Si-H and C-H bonds in a-SiC:H [1] and SiC converted graphite [2], we suggest that this center is related to carbon dangling bonds created by the effusion of hydrogen during the dry heat-treatment. We will compare the activation energy for the hydrogen depassivation of our center with that found for other C-H and Si-H systems.

scholarly journals Semiconducting properties of Ge-doped BaSnO3 ceramic

2019 ◽  
Author(s):  
Roberto Köferstein
Keyword(s):  
Band Gap ◽  
Optical Band Gap ◽  
Wide Band ◽  
Rate Of Change ◽  
Wide Band Gap ◽  
Electrical And Optical Properties ◽  
Optical Band Gaps ◽  
Semiconducting Properties ◽  
Semiconductor Behavior ◽  
Maximum Conductivity

The electrical and optical properties of Ge-doped BaSnO3 ceramics sintered at varioustemperatures have been investigated to determine their semiconductor behavior. The electricalconductivity of Ge-doped BaSnO3 samples increases with increase in temperature, confirmingthat the samples exhibit a semiconductor behavior. A maximum conductivity value of6.31 × 10−9 S/cm was observed for the sample sintered at 1200 °C. The optical band gaps ofthe Ge-doped BaSnO3 samples were determined by means of reflectance spectra. The variation of optical band gap with temperature was analyzed using Eg(T) = Ego + βT relation. The rate of change of the band gap β of BaSn0.99Ge0.01O3 was found to be 7.6 × 10−4 (eV/°C).A minimum optical band gap value of 2.95 eV was observed for the sample sintered at 1400 °C. It is evaluated that BaSn0.99Ge0.01O3 is a wide band gap semiconductor and its semiconducting properties change with sintering temperature.

scholarly journals Microwave Dielectric Properties of β-CaSiO3 Glass–Ceramics Prepared Using Two-Step Heat Treatment

Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2180
Author(s):  
Jin-Seok Baek ◽  
Nak-Beom Jo ◽  
Eung-Soo Kim
Keyword(s):  
Heat Treatment ◽  
Dielectric Properties ◽  
Glass Ceramics ◽  
Microwave Dielectric Properties ◽  
Dominant Factor ◽  
Conventional Solid State Reaction ◽  
Microwave Dielectric ◽  
Treatment Conditions ◽  
Heat Treated ◽  
Step Heat Treatment

The microwave dielectric properties of β-CaSiO3 glass–ceramics are compared with those of α-CaSiO3 ceramics. β-CaSiO3 is prepared using glass–ceramics method with two-step heat treatment at 730 °C for 1–7 h and at 900 °C for 3 h, and α-CaSiO3 is prepared using conventional solid-state reaction and sintered at 1460–1500 °C for 3 h. With increasing holding time at 730 °C, the degree of crystallisation and Qf of the β-CaSiO3 glass–ceramics increased. The β-CaSiO3 specimens heat-treated at 730 °C for 3 h and 900 °C for 3 h exhibit the following dielectric properties: K = 6.57, TCF = −36.22 ppm/°C, and Qf = 52,400 GHz (highest) for the entire range of heat treatment conditions. The Qf difference between β-CaSiO3 and α-CaSiO3 could be explained by the bond characteristics using Rietveld refinement. FT-IR analysis shows that the Ca–O bond is the dominant factor for the Qf of CaSiO3 ceramics compared to the Si–O bond. The higher Qf of β-CaSiO3 than that of α-CaSiO3 can be attributed to the higher bond strength of Ca–O for β-CaSiO3 than that for α-CaSiO3.

scholarly journals Vapor-phase stoichiometry and heat treatment of CdTe starting material for physical vapor transport

1998 ◽  
Vol 183 (4) ◽  
pp. 519-524 ◽  
Author(s):  
Ching-Hua Su ◽  
Yi-Gao Sha ◽  
S.L. Lehoczky ◽  
Hao-Chieh Liu ◽  
Rei Fang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Vapor Phase ◽  
Vapor Transport ◽  
Starting Material ◽  
Physical Vapor Transport

scholarly journals Effect of heat treatment on morphology and dielectric properties of PE cable insulation material

2017 ◽  
Author(s):  
Hossein Ghorbani ◽  
Tanbhir Hoq ◽  
Hans Edin
Keyword(s):  
Heat Treatment ◽  
Dielectric Properties ◽  
Electric Fields ◽  
Dielectric Spectroscopy ◽  
Sample Thickness ◽  
Insulation Material ◽  
Scanning Calorimetry ◽  
Conduction Current ◽  
Dsc Measurements ◽  
High Electric Fields

<p>It is known that the heat treatment process in the<br />production of extruded cables, affects the electrical<br />properties of polymeric insulation materials; this effect<br />is via two main phenomena; first, it leads to diffusion<br />and removal of polar substances from the system;<br />second, it affects the polymer morphology by increasing<br />the polymer chain relaxation and creation of crystallites,<br />hence increasing the crystallinity of the material.<br />In this study, thick pressed samples with additive free<br />low density polyethylene (LDPE) insulation material<br />were heat treated at different conditions for different<br />periods of times. Differential scanning calorimetry<br />(DSC) measurements confirmed that heat treatment<br />leads to higher crystallinity and higher lamella thickness<br />in LDPE. Dielectric properties of the material was<br />studied by conduction current measurement and<br />dielectric spectroscopy.<br />Conduction current of samples with different heat<br />treatment times was measured at high electric fields<br />which shows that the conduction current of LDPE is<br />affected by heat treatment. Generally, the apparent<br />conductivity decreases by heat treatment.<br />Dielectric spectroscopy measurements show that heat<br />treatment does not have a significant effect on real and<br />imaginary permittivity of the polymer. Interestingly, an<br />increase in the sample thickness via heat treatment, was<br />observed both by sample thickness related to the<br />memory effects in the polymer which needs to be taken<br />into consideration for accurate capacitance<br />measurements.</p>

Effects of S-Doping and Subsequent Annealing on Photoluminescence around 1.54ųm from Er-Containing ZnO

2005 ◽  
Vol 475-479 ◽  
pp. 1125-1128
Author(s):  
Zhen Zhou ◽  
N. Sato ◽  
T. Komaki ◽  
Atsushi Koizumi ◽  
T. Komori ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Band Gap ◽  
Local Structure ◽  
Wide Band ◽  
Subsequent Annealing ◽  
Wide Band Gap ◽  
Gas Atmosphere ◽  
Pl Intensity

The wide band-gap semiconductor, ZnO, has been proposed as one of the good host for Er3+ ions. In this investigation S was doped into the Er-containing ZnO specimens through the heat treatment in a H2S gas atmosphere. After sulfurization, the photoluminescence (PL) peak centered at 675nm from the ZnO host became much weaker, and accordingly the absorption peaks of Er3+ at 526nm, 550nm, and 665 nm became weaker. Also, the PL intensity around 1.54µm decreased after the sulfurization. However, when the sulfurized specimens were annealed at 1000oC in air, the PL intensity increased by about 3 times. The effects could be due to the modification of the local structure around the Er3+ ions in ZnO.

Effect of Varying Oxidation Parameters on the Generation of C-Dangling Bond Centers in Oxidized SiC

1999 ◽  
Vol 572 ◽  
Author(s):  
P. J. Macfarlane ◽  
M. E. Zvanut
Keyword(s):  
Heat Treatment ◽  
Field Effect Transistors ◽  
Wide Band ◽  
Hydrogen Release ◽  
Wide Band Gap ◽  
Paramagnetic Resonance ◽  
Dry Heat ◽  
Dry Heat Treatment ◽  
Oxidation Parameters ◽  
Mos Structures

ABSTRACTSiC is perhaps the most appropriate material to replace Si in power-metal-oxidesemiconductor- field-effect-transistors (MOSFETs), because, unlike the other wide band-gap semiconductors, SiC can be thermally oxidized similarly to Si to form a SiO2 insulating layer. In our studies of oxidized SiC, we have used electron paramagnetic resonance (EPR) to identify Cdangling bonds generated by hydrogen release from C-H bonds. While hydrogen's effect on SiCbased MOSFETs is uncertain, studies of Si-based MOSFETs indicate that it is important to minimize hydrogen in MOS structures. To examine the role of hydrogen, we have studied the effects of SiC/SiO2 fabrication on the density of C-related centers, which are made EPR active by a dry heat-treatment. Here we examine the starting and ending procedures of our oxidation routine. The parameter that appears to have the greatest effect on center density is the ending step of our oxidation procedure. For example, samples that were removed from the furnace in flowing O2 produced the smallest concentration of centers after dry heat-treatment. We report on the details of these experiments and use our results to suggest an oxidation procedure that limits center production.

TEM and cathodoluminescence of precipitates in II-VI semiconductors

1988 ◽  
Vol 46 ◽  
pp. 488-489
Author(s):  
Joanna L. Batstone
Keyword(s):  
Crystal Growth ◽  
Band Gap ◽  
Local Strain ◽  
Wide Band ◽  
Optoelectronic Device ◽  
Wide Band Gap ◽  
Bulk Crystal Growth ◽  
Transmission Electron ◽  
Device Applications ◽  
Stoichiometry Control

Interest in II-VI semiconductors centres around optoelectronic device applications. The wide band gap II-VI semiconductors such as ZnS, ZnSe and ZnTe have been used in lasers and electroluminescent displays yielding room temperature blue luminescence. The narrow gap II-VI semiconductors such as CdTe and HgxCd1-x Te are currently used for infrared detectors, where the band gap can be varied continuously by changing the alloy composition x.Two major sources of precipitation can be identified in II-VI materials; (i) dopant introduction leading to local variations in concentration and subsequent precipitation and (ii) Te precipitation in ZnTe, CdTe and HgCdTe due to native point defects which arise from problems associated with stoichiometry control during crystal growth. Precipitation is observed in both bulk crystal growth and epitaxial growth and is frequently associated with segregation and precipitation at dislocations and grain boundaries. Precipitation has been observed using transmission electron microscopy (TEM) which is sensitive to local strain fields around inclusions.

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