A free-space measurement of complex permittivity of doped silicon wafers using transmission coefficient at microwave frequencies
01 Jul 2004-pp 1-4
TL;DR: In this paper, a contactless and non-destructive method is presented to characterize p-type and n-type silicon semiconductor wafers using a spot-focused free-space measurement system.
Abstract: A contactless and non-destructive method is presented to characterize p-type and n-type silicon semiconductor wafers using a spot-focused free-space measurement system. In this method, the free-space reflection and transmission coefficients, S 11 and S 21 , are measured for silicon wafer sandwiched between two teflon plates which are quarter-wavelength at mid-band. The actual reflection and transmission coefficient, S 11 and S 21 of the silicon wafers are then calculated from the measured S 11 and S 21 by using ABCD matrix transformation in which the complex permittivity and thickness of the teflon plates are known. Complex permittivity are computed using only the transmission coefficient, S 21 . From the complex permittivity, the resistivity and conductivity can be obtained. Results are reported in the frequency range of 9–12.5 GHz. The dielectric constant obtained were close to published values for silicon wafers and the resistivities agree well with that measured by other conventional method.
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01 Nov 2011
TL;DR: In this article, a study of single layer radar absorbing material made using coconut shell-based activated carbon was presented, where flaxane-80 was used as binder and was mixed to give 10, 15, 20, 20 and 25 wt% variation of activated carbon obtained from coconut shell to study the microwave properties of the material.
Abstract: This paper presents a study of single layer radar absorbing material made using coconut shell-based activated carbon. Flaxane-80 was used as binder and was mixed to give 10 wt%, 15 wt%, 20 wt% and 25 wt% variation of activated carbon obtained from coconut shell to study the microwave properties of the absorber material. An industry standard electromagnetic simulator was used to predict the absorber behaviour, while microwave non-destructive testing (MNDT) technique was used to measure microwave properties and reflection characteristics of the samples. The relative permittivity of 25 wt% carbon sample was found to be the highest with a value of 12. The sample also has the highest tan δ of 0.4. The thicknesses of absorbers made of 25 wt% carbon were varied at 3.2 mm, 6.4 mm, 9.6 mm and 13.8 mm to determine the reflection characteristics. The 6.4 mm sample was found to offer minimum reflection at 9.6 GHz with −22 dB reflection loss. Sample 9.6 mm has a minimum reflection loss of −17dB at 11.3 GHz. The results of this study offer great opportunities for RF application seeking for low cost and light-weight radar absorber material using coconut-shell.
17 citations
05 Oct 2004
TL;DR: An algorithm using only transmission measurements to calculate the complex permittivity of p-type and n-type silicon semiconductor wafers using a spot-focused free-space measurement system was developed in this article.
Abstract: An algorithm using only transmission measurements to calculate the complex permittivity of p-type and n-type silicon semiconductor wafers using a spot-focused free-space measurement system was developed The dielectric constant obtained was close to published values for silicon wafers The errors associated with the measurement of the complex permittivity values are discussed, and comparisons between the measured and calculated magnitude and phase of the forward reflection and transmission coefficients are presented In this method, the free-space reflection and transmission coefficients, S/sub 11/ and S/sub 21/, are measured for a silicon wafer sandwiched between two teflon plates which are quarter-wavelength at midband The actual reflection and transmission coefficient, S/sub 11/ and S/sub 21/ of the silicon wafers are then calculated from the measured S/sub 11/ and S/sub 21/ by using ABCD matrix transformation in which the complex permittivity and thickness of the teflon plates are known Results are reported in the frequency range of 8-125 GHz
4 citations
01 Dec 2008
TL;DR: A microwave non-destructive testing (MNDT) method to determine the ripeness of Siamese mangoes at a frequency range of 18 to 26.5 GHz (K-Band) using free space microwave measurement (FSMM) system is presented in this article.
Abstract: This project presents a microwave non-destructive testing (MNDT) method to determine the ripeness of Siamese mangoes at a frequency range of 18 to 26.5 GHz (K-Band) using free space microwave measurement (FSMM) system. The basic components of the FSMM system are spot focusing horn lens antennas, a vector network analyzer (VNA) and a computer. In this method, the free space reflection, S11 and transmission, S21 coefficients are measured for the samples sandwiched between two Teflon plates that are quarter wavelengths at mid-band. The thru, reflect and line (TRL) calibration technique is used to eliminate the effect of undesirable multiple reflections. The extracted S11 and S21 are keyed in a developed algorithm to calculate the complex permittivity of moisture contents within the samples. Results have shown that the dielectric constants for ripe and unripe mangoes are between 26.3 to 29.5 and 26.1 to 29.2 respectively. Other parameters including loss factor and loss tangent are also discussed.
4 citations
Cites background or methods from "A free-space measurement of complex..."
...If εq* and dq are the complex permittivity and thickness of the Teflon plate, the ABCD matrix for the Teflon plate is given by [3]:...
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...Recently, characterization of silicon wafers for p-type and n-type had been reported extensively by these authors [1-4]....
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TL;DR: The photoinduced microwave complex permittivity of a highly resistive single-crystal silicon wafer was extracted from a bistatic free-space characterization test bench operating in the 26.5-40 GHz frequency band under CW optical illumination at wavelengths of 806 and 971 nm as mentioned in this paper .
Abstract: The photoinduced microwave complex permittivity of a highly resistive single-crystal silicon wafer was extracted from a bistatic free-space characterization test bench operating in the 26.5–40 GHz frequency band under CW optical illumination at wavelengths of 806 and 971 nm. Significant variations in the real and imaginary parts of the substrate’s permittivity induced by direct photoconductivity are reported, with an optical power density dependence, in agreement with the theoretical predictions. These experimental results open the route to ultrafast system reconfiguration of microwave devices in integrated technology by an external EMI-protected and contactless control with unprecedented performance.
References
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Book•
01 Dec 1995
TL;DR: Theory of dielectric measuring techniques and their applications as mentioned in this paper Theoretical and practical applications of die-lectric materials include: insulation strength of high pressure gases and of vacuum liquid dielectrics plastics as dielectors ceramics dielectrices in equipment, capacitors in capacitors rubber and plastics in cables problems of the cable engineer, and the requirements of the armed forces.
Abstract: Theory dielectric measuring techniques dielectric materials and their applications - dielectric materials insulation strengths of high pressure gases and of vacuum liquid dielectrics plastics as dielectrics ceramics dielectrics in equipment dielectrics in power and distribution equipment dielectrics in electronic equipment dielectrics in capacitors rubber and plastics in cables problems of the cable engineer dielectric materials as devices rectifiers piezoelectric transducers and resonators magnetic and dielectric amplifiers memory devices dielectric requirements of the armed forces tables of dielectric materials
1,614 citations
"A free-space measurement of complex..." refers methods in this paper
...Teflon had been measured around the same frequencies by Von Hippel [7] using the short-circuited-line....
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TL;DR: In this article, a free-space measurement system operating in the 8.2-40 GHz frequency range is used to measure the reflection and transmission coefficients, S/sub 11/ and S/ sub 21/, of planar samples.
Abstract: A free-space measurement system operating in the 8.2-40-GHz frequency range is used to measure the reflection and transmission coefficients, S/sub 11/ and S/sub 21/, of planar samples. The complex electric permittivity and the magnetic permeability are calculated from the measured values of S/sub 11/ and S/sub 21/. The measurement system consists of transmit and receive horn lens antennas, a network analyzer, mode transitions, and a computer. Diffraction effects at the edges of the sample are minimized by using spot-focusing lens antennas. Errors due to multiple reflections between antennas via the surface of the sample are corrected by using a free-space TRL (thru, reflect, line) calibration technique. For thin, flexible samples, the sample had to be sandwiched between two half-wavelength (at mid-band) quartz plates to eliminate sagging. Results are reported in the frequency range of 8.6-13.4 GHz for materials such as Teflon, sodium borosilicate glass, and microwave-absorbing materials. >
743 citations
"A free-space measurement of complex..." refers methods in this paper
...If the ABCD matrix of the assembly is denoted as [A], the sample [A] and the teflon [A], then following relationship is obtained [6]...
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...PVC had also been measured around the same frequencies by Ghodgaonkar [6] using free-space technique....
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...21, we refer to Ghodgaonkar et al [6]....
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...In deriving the equations for calculating complex permittivity, ( ) using the transmission coefficient, S j* 21, we refer to Ghodgaonkar et al [6]....
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TL;DR: In this article, the complex microwave conductivity of lightly-doped n and p-type silicon and genmanium was measured by observing the reflectivity of the circular T E01 mode at 48 GHz and were thus free of errors caused by the impedance of the waveguide.
Abstract: This paper presents measurements of the complex microwave conductivity of lightly‐doped n‐ and p‐type silicon and genmanium as functions of impurity concentration and of temperature between 77° and 300°K. The measurements were obtained by observing the reflectivity of the circular T E01 mode at 48 GHz and are thus free of errors caused by the impedance of the waveguide‐sample contact. Analysis utilized currently accepted scattering models including ionized impurity scattering, intravalley acoustic and optical mode scattering, and intervalley scattering. The results are used to investigate the temperature and doping dependence of the average relaxation time and the conductivity ``effective'' mass.
47 citations
"A free-space measurement of complex..." refers background in this paper
...To date, various versions of the microwave measurement techniques are reported for the characterization of semiconductors [1-5] but none have used free-space method which is contactless and nondestructive....
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TL;DR: It was found that the detection of the moisture system is now almost complete, which effectively shifts the pave- emphasis from the construction of new pavements to sys- ment (21).
Abstract: like cracking and ravelling. The existence of excess mois- ture affects both the elastic modulus and fatigue life of the asphaltic concrete pavements. Measurement of the moisture content in asphaltic con- URING the 1960s and 1970s, the construction of the Crete pavement is still limited. Although nuclear gauges DInterstate Highway System in the United States was have been used to detect the moisture content in hot-mix the largest public works project in history. The highway concrete, it was found that the detection of the moisture system is now almost complete. This effectively shifts the 'Ontent was affected by the 'Ontent Of the pave- emphasis from the construction of new pavements to sys- ment (21. tern preservation: maintenance and rehabilitation. For Since the 1960~~ there has been a gradual trend toward maintenance and rehabilitation purposes, information the use of electromagnetic techniques for pavement in- methods, depending on the measurement requirements. used to detect voids underneath reinforced and portland
46 citations
"A free-space measurement of complex..." refers background in this paper
...79% of the original value and is determined from the following equation [8],...
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TL;DR: In this paper, an attempt has been made to improve the reflection results from an analysis of the parameters of a circle diagram for reflection coefficient obtained on using a variable reactive termination after the semiconductor-filled waveguide section.
Abstract: Complex microwave conductivity of 9 /spl Omega/ /spl dot/ cm p-type silicon samples has been measured using conventional reflection and transmission bridges to examine their relative advantages and disadvantages. An attempt has been made to improve the reflection results from an analysis of the parameters of a circle diagram for reflection coefficient obtained on using a variable reactive termination after the semiconductor-filled waveguide section. In conformity with the calculated accuracy attainable from different types of measurement under the actual experimental condition, using commercial standards, the dielectric constant for the sample was found to be scattered over a region of /spl plusmn/0.4. It has been concluded that because of lack of accuracy in commercial standards for attenuation and phase shift, the potential accuracy of the conventional microwave methods falls too short of its mark to make any detinite conclusion about the effective mass of carriers in semiconductors at room temperatures.
17 citations