Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Patent
1995-09-01
1997-05-06
Wieder, Kenneth A.
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
29593, 204195, 324663, G01R 2726, G01R 3126
Patent
active
056274793
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for determining characteristic electrical properties of semi-conducting materials wherein the time or frequency dependent electrical impedance or admittance is measured. The invention also relates to an apparatus far carrying out the method.
A number of bulk and surface parameters characterize the electrical properties of a given piece of material. These parameters include the dielectric constant .epsilon. of the material, the difference .DELTA..mu..sup.ch in the chemical potential of the bulk of a material and the chemical potential of its surface and/or of metal electrode--material surface interface, the density of the majority and minority electrical mobile charge carriers N and N.sub.min, respectively, in the bulk of the material, the electrical mobility .mu. of the majority electrical mobile charges in the bulk of the material and the electrical mobility .mu..sub.min of minority mobile charge carriers, the surface and bulk emission and capture rates E.R and C.R., respectively, for mobile positive and negative charge carriers characterizing the effect of surface and bulk localized states within the band gap, when they are present, on the electrical transport.
Depending on the experimental arrangement the present invention can be used either to characterize the whole piece of material (integral characterization), or alternatively to map the variations of the above mentioned electrical material parameters, i.e. some of them, all of them and/or various combinations of them such as the specific resistivity .rho.: 1/N.e..mu. as a function of the position of the measuring head and measuring point on the surface of the material be that a piece of semi-conductor, insulator or a semi-conducting wafer.
There exists a number of experimental methods today that are being used for the experimental determination of the above mentioned electrical material parameters .DELTA..mu..sup.ch, .epsilon., N and .mu., in semi-conductors and insulators. Table 1 illustrates to the best knowledge of the inventors the range of the experimental methods (the list not being exhaustive) that are relevant to the present invention.
The literature about each of these experimental methods is vast. The references (1), (2) and (3) relate to Standard Electrical Impedance Experimental method and have been chosen as sufficient background reference since the present invention relates directly to this particular experimental method.
The known experimental methods used today for the determination of the parameters suffer from a number of disadvantages the main of which can be summarized as follows: of the parameters simultaneously and independently in a single experiment. order to be able to determine some of the parameters in question, for example a combination of the Hall effect and the d.c. four probe resistivity measurements is required if both .mu. and N are to be obtained. indirect. The determination of .DELTA..mu..sup.ch by Photoemission, for example, is measured in two steps. First the work function of the un-contacted surface of the material is measured and then the measurement of the work function of the contacting metal is performed. The difference between the two work functions is then assumed to be a measure of the .DELTA..mu..sup.ch when the material in question is contacted by the given metal. establish (PEE,FTIR, FTIPL), requiring either an ultra high vacuum environment (CP,TEE,PEE), liquid Helium temperatures (FTIR, FTIPL) or magnetic fields (HE). methods can often be considered only as qualitative in relation to the determination of the numerical values of the parameters in question. 4PDCR, HE and TOF) either neglect totally or treat inadequately the effects of the electrical contact regions, the effects of the real surfaces of the material under investigation (surfaces that are part of the electrical measuring circuit), the effects of the metal electrode--material surface regions and the effects of the depletion regions within the material under investigation on the calculated values of
REFERENCES:
patent: 3605015 (1971-09-01), Copeland, III
patent: 4028207 (1977-06-01), Faktor et al.
patent: 5103183 (1992-04-01), Klein et al.
Capacitance Measurement for ASIC QC; Electronic Engineering; Jun. 1987; pp. 14, 19.
Use of Impedance Meters in Dielectric Measurements; Solodukha Et Al.; Plenum Publishing Corporation; 1983; pp. 521-522.
Vedde Jan
Viscor Petr
Bowser Barry C.
Viscor Peter
Wieder Kenneth A.
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