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Showing papers on "Van der Pauw method published in 1993"


Journal ArticleDOI
TL;DR: In this article, the conductivity of BaCe0.9Gd0.95, previously reported only up to 800°C, was measured up to 1200°C using the van der Pauw technique.

40 citations


Journal ArticleDOI
TL;DR: In this article, a thin zinc oxide film (0.3-1 μm) was deposited on quartz and silicon substrates using a spray-CVD system developed in our laboratory.

30 citations


Journal ArticleDOI
TL;DR: In this paper, single crystal wafers enriched with 10B with an area of 20 x 20 mm2 and a thickness of 200-300 μm were prepared by chemical vapor deposition using the 10B2H6-PH3 system.

24 citations


Journal ArticleDOI
TL;DR: A multiple-step, low-temperature boron-ion implantation procedure that used three different implantation energies to produce an approximately uniformly doped p-type layer of about 200 nm thickness produced the best combination of carrier concentration and mobility.
Abstract: Natural type-IIa diamonds were implanted with either boron alone, carbon alone, or carbon plus boron at 77, 300, or 800 K. van der Pauw resistivity and Hall effect measurements of carrier concentration and mobility were made as a function of temperature to determine the most effective implantation conditions for semiconducting device applications. No measurable dopant incorporation occurs for the 800-K implant. The highest carrier concentration and mobility are observed when the implantation is carried out at 77 K. It is further shown that a significant increase in the hole concentration occurs when carbon is implanted prior to boron. These measurements provide direct confirmation of the theoretical predictions of Prins and co-workers. It is shown, however, that the carbon co-implant results in a decreased hole mobility. A multiple-step, low-temperature boron-ion implantation procedure that used three different implantation energies to produce an approximately uniformly doped p-type layer of about 200 nm thickness (as verified by secondary-ion-mass spectrometry on a separate sample) produced the best combination of carrier concentration and mobility. The resulting doped layer was used in the fabrication of an insulated-gate field-effect transistor that demonstrated current saturation and pinch-off at room temperature.

21 citations


Journal ArticleDOI
TL;DR: In this article, the first results of the use of a new precursor, diisopropylantimonyhydride (DIPSbH), (C 3 H 7 ) 2 SbH, were given.

19 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the material properties of 2-μm-thick InxGa1−xAs epilayers grown on GaAs with 0.28≤x≤1 were investigated.
Abstract: The material properties of 2‐μm‐thick InxGa1−xAs epilayers grown on GaAs with 0.28≤x≤1 were investigated. It was found that for x≥0.5, the material quality of the larger lattice‐mismatched heterojunction recovers, as evidenced by cross‐sectional transmission electron microscopy (XTEM) and double‐crystal x‐ray diffraction (DXRD). Magnetophotoconductivity measurements were performed on InxGa1−xAs epilayers with 0.75≤x≤1. The dependence of both the cyclotron resonance linewidth and the carrier relaxation time on the material quality is consistent with the XTEM and DXRD results. The transport properties of InxGa1−xAs epilayers with 0.75≤x≤1 were studied using temperature‐dependent van der Pauw measurements. It was found that the electron mobility in the low‐temperature range is determined by a combination of ionized impurity and dislocation scatterings. The contribution of dislocation scattering to ternary InGaAs epilayers is larger than that to InAs, although InAs has a larger lattice mismatch with respect t...

19 citations


Journal ArticleDOI
TL;DR: In this article, the optical absorption coefficient of thin films of CuGaxIn1-xSe2 was determined from the measured transmittance and reflectance in the wavelength range 0.4-2.0 µm.
Abstract: Thin films of CuGaxIn1-xSe2 were produced by laser-assisted evaporation. From X-ray diffraction analyses, these films have chalcopyrite structure and the lattice parameters were estimated. The optical absorption coefficient of the CuGaxIn1-xSe2 films were determined from the measured transmittance and reflectance in the wavelength range 0.4–2.0 µm. Hot probe analyses indicate that these thin films have p-type conduction. The Van der Pauw measurements show that the rasistivity increases with the decrease of indium content.

18 citations


Journal ArticleDOI
TL;DR: Carbon-doped GaAs and Al x Ga 1-x As epilayers have been grown by solid source MBE using resistively heated, pyrolytic graphite filaments for the carbon source.

15 citations


Journal ArticleDOI
TL;DR: Carbon and silicon-doped CdTe have been studied by charged particle activation heavy ion induced X-ray emission and secondary ion mass spectroscopy to determine the impurities present at low concentrations.
Abstract: Carbon- and silicon-doped CdTe have been studied by charged particle activation heavy ion induced X-ray emission and secondary ion mass spectroscopy to determine the impurities present at low concentrations. Electrical characteristics have been investigated by thermally stimulated current and the Van der Pauw resistivity measurements, in order to correlate the impurity concentrations and electrical behaviours.

13 citations



Journal ArticleDOI
TL;DR: In this paper, the resistivity correction factor (RCF) is derived analytically for correcting data measured by means of the four-ring probe method and for obtaining resistivity of the sample, and the properties of the RCF are discussed on the basis of the theoretical analysis.
Abstract: The four-ring probe method which was devised as a method of measuring resistivity is described. This method is applicable to the system consisting of a circular disk sample and a four-ring probe array. The resistivity correction factor (RCF), which is necessary for correcting data measured by means of the four-ring probe method and for obtaining the resistivity of the sample, is derived analytically. The properties of the RCF are discussed on the basis of the theoretical analysis. It is demonstrated by the experimental results that (i) the RCF corrects data accurately, (ii) it is insensitive to the shape of the sample and the measurement position as long as the thickness of the sample is less than the probe spacing, and (iii) the four-ring probe method is compatible with the four-point probe method.

Journal ArticleDOI
TL;DR: In this article, the authors measured at temperatures from 15 to 305 K in n−GaAs van der Pauw samples irradiated by fast reactor neutrons and found that the inverse mobility increased as a result of neutron irradiations over the whole range of temperature; the increase is attributed to the increased scattering from neutron induced charged defects.
Abstract: Mobility changes were measured at temperatures from 15 to 305 K in n‐GaAs van der Pauw samples irradiated by fast reactor neutrons. The inverse mobility values, obtained from the variable temperature Hall measurements were fitted using the relation μ−1=AT−3/2+BT3/2. The inverse mobility was found to increase as a result of neutron irradiations over the whole range of temperature; the increase is attributed to the increased scattering from neutron induced charged defects. The values of A found by the least square fitting were used to estimate the increased scattering effect from neutron‐induced ionized defects after each step of irradiation. It is concluded that in order to explain the experimental results presented here, the creation of multiply charged defects must be considered.

Journal ArticleDOI
TL;DR: In this article, a thin, strongly disturbed surface dislocations were produced by lapping or other mechanical treatment to prepare ohmic contacts on high-resistivity CdTe for Hall effect measurements.
Abstract: There are large variations in the density and distribution of dislocations in CdTe crystals. The dislocation density was determined by etching. For the electrical measurements (Hall effect and conductivity by the Van der Pauw method), crystal regions were selected which showed extremely different dislocation densities. The dislocation density did not noticeably affect the bulk electrical properties. For the preparation of ohmic contacts, a thin, strongly disturbed surface dislocations were produced by lapping or other mechanical treatment to prepare ohmic contacts on high-resistivity CdTe for Hall effect measurements.

Journal ArticleDOI
TL;DR: In this article, metalorganic vapor phase epitaxy of InP with extremely low V/III ratios less than 10 was successfully carried out by using tertiary butylphosphine, and detailed electrical and optical properties were investigated for the first time.
Abstract: Metalorganic vapor phase epitaxy of InP with extremely low V/III ratios less than 10 was successfully carried out by using tertiarybutylphosphine, and detailed electrical and optical properties were investigated for the first time. Featureless surface morphology was obtained even with a V/III ratio of as low as 3. Good electrical properties, such as carrier concentrations of about 6×1014 cm−3 and electron Hall mobilities more than 30 000 cm2/V s measured at 77 K were confirmed, although both Van der Pauw and low‐temperature photoluminescence results proved the increased acceptor concentrations in the low V/III ratio range.

Journal ArticleDOI
TL;DR: In this article, liquid phase epitaxy of GaAs from Bi melt was studied for growth temperatures between 670 and 750 C. All epitaxial layers were n-type and exhibit low compensation and electron mobilities up to 6×104 cm2/V
Abstract: Liquid phase epitaxy of GaAs from Bi melt was studied for growth temperatures between 670–750○C. The layers were characterized by Van der Pauw and photoluminescence measurements. All epitaxial layers were n‐type and exhibit low compensation and electron mobilities up to 6×104 cm2/V s at 77 K. A gradual increase in the n‐type doping was observed with growth temperature. Intentional doping of GaAs with Sn leads to a Sn distribution coefficient ∼60 times larger for the Bi melt in comparison to the Ga melt. Extremely low compensation of the Sn‐doped layers (K≤0.1 for Nd=2.5×1017 cm−3) is obtained.

Journal ArticleDOI
TL;DR: In this article, a geometric factor applicable to a wide range of device geometries of the van der Pauw dual configuration is presented, which allows a direct retrieval of the Hall mobility in a single measurement of the magnetic-field-induced imbalance in output current.
Abstract: A geometric factor applicable to a wide range of device geometries of the van der Pauw dual configuration is presented. Such a configuration allows a direct retrieval of the Hall mobility in a single measurement of the magnetic-field-induced imbalance in output current. In view of scaling considerations, the geometric factor is characterized simply in terms of device aspect ratio (L/W) and relative electrode separation (d/W). The geometric factor, which is based on numerical computations, overcomes the limitations inherent in the existing form that has been analytically obtained for an infinitesimally small electrode separation. Hence, it is now possible to design practical device geometries which readily lend themselves to in situ measurement and characterization of the material or process in question, without being constrained by photolithography limitations. >

Journal ArticleDOI
TL;DR: In this paper, the van der Pauw Hall effect and resistivity measurements as a function of temperature from 8 to 400 K have been used to investigate the electrical transport properties of phosphorus-doped p-type CdTe single crystals and phosphorus-ion-beam doped, homoepitaxial thin films.
Abstract: Electrical transport properties of phosphorus‐doped p‐type CdTe single crystals and phosphorus‐ion‐beam doped, homoepitaxial thin films have been investigated by means of van der Pauw Hall effect and resistivity measurements as a function of temperature from 8 to 400 K Analysis of the data indicates a maximum doping level greater than 2×1017 cm−3 in the films, at least as high as in the single crystals Phosphorus has an ionization energy of about 40 meV, the degree of compensation is smaller in the films, room temperature mobilities of the films are lower than those for single crystals by about 20%, and the temperature dependence of mobility is similar for both crystals and films Impurity scattering is dominant at lower temperatures and polar mode scattering is dominant at higher temperatures with a maximum mobility at 150–190 K Both the single crystals and the ion‐assisted doped films show a temperature independent resistivity at temperatures below 40 K, indicating the presence of impurity band condu

Journal ArticleDOI
TL;DR: Chlorine has been used successfully for the first time for n-type doping of CdTe epitaxial layers (epilayers) grown by photo-assisted molecular beam epitaxy as mentioned in this paper.
Abstract: Chlorine has been used successfully for the first time for n-type doping of CdTe epitaxial layers (epilayers) grown by photo-assisted molecular beam epitaxy Similar to n-type doping of ZnSe layers, ZnCl 2 has been used as source material The free-carrier concentration can be varied over more than three orders of magnitude by changing the ZnCl 2 oven temperature Peak mobilities are 4700 cm 2 V −1 s −1 for an on concentration of 2×10 16 cm −3 and 525 cm 2 V −1 s −1 for 2×10 18 cm −3 The electrical transport data obtained by Van der Pauw configuration and Hall structure measurements are consistent with each other, indicating a good uniformity of the epilayers In photoluminescence the donor-bound-exciton emission dominates for all chlorine concentrations This contasts significantly with results obtained for indium doping, commonly used for obtaining n-type CdTe epilayers The superiority of chlorine over indium doping and the influence of growth parameters on the behaviour of CdTe:Cl layers will be discussed on the basis of transport, luminescence, secondary ion mass spectroscopy and X-ray photoelectron spectroscopy data

Journal ArticleDOI
TL;DR: In this article, a pulsed XeCl excimer laser is used to grow ideally strained heteroepitaxial Si1-xGex/Si layers with Boron dopant.

Journal ArticleDOI
TL;DR: In this article, the van der Pauw method and low-temperature photoluminescence (77 K PL) spectra of pseudomorphic GaAs/InyGa1−yAs/AlGaAs modulation-doped field effect transistor-type heterostructures grown by molecular beam epitaxy were compared.
Abstract: Hall electrical properties measured by the van der Pauw method and low‐temperature photoluminescence (77 K PL) spectra of pseudomorphic GaAs/InyGa1−yAs/AlGaAs modulation‐doped field‐effect transistor‐type heterostructures grown by molecular‐beam epitaxy were compared. By using these two characterization methods, the influences of the growth temperature Ts , the InGaAs quantum‐well channel thickness dch , and its indium composition y were studied. Interesting correlations were established between their 77 K PL spectra and their transport properties measured either in the dark or under white‐light illumination. The PL spectra exhibit one or two bands which are attributed to transitions from electronic states belonging to the first or to the second subband formed in the conduction quantum well, the second transition at higher energy being observed only when the two‐dimensional concentration exceeds a critical value nc which, in the dark, is ∼2.4×1012 cm−2 (i.e., dch≊108 A) for the homogeneously doped heteros...

Journal ArticleDOI
TL;DR: In this article, the van der Pauw method was compared to low-temperature photoluminescence (77 K) spectra of GaAs/SPS/AlGaAs modulation-doped field effect transistor-type heterostructures.
Abstract: The molecular‐beam epitaxial growth conditions of (N+1)(InAs)m/N(GaAs)n short period superlattices (SPSs) on GaAs substrates have been optimized. Hall electrical properties measured by the van der Pauw method were compared to low‐temperature photoluminescence (77 K PL) spectra of GaAs/SPS/AlGaAs modulation‐doped field‐effect transistor‐type heterostructures. By using these two characterization methods, the influences of the growth temperature Ts, of the SPS channel thickness dch and of its average indium composition ym were studied. Interesting correlations were established between their optical and their transport properties measured at 77 K either in the dark or under white‐light illumination. The thickness m of the InAs layers was varied in the range 0.57 to 1.7 and sharp optimum properties were obtained slightly above m=1 monolayer. The PL spectra exhibit one or two bands which are attributed to transitions from electronic states belonging to the first or to the second subband formed in the conduction...

Journal ArticleDOI
TL;DR: In this article, photo assisted hot-wall-beam epitaxy using Li3N as a dopant source was used to grow high-conducting p-type CdTe films.
Abstract: Highly conducting p‐type CdTe films were grown by photoassisted hot‐wall‐beam epitaxy using Li3N as a dopant source. Doping levels can be controlled from p=4×1016 to 2×1018 cm−3, as determined by Van der Pauw measurements. The hall mobility ranges from 30 to 100 cm2/V s, depending on the hole concentration. Photoassisted growth enhances the incorporation of dopants by one order of magnitude and decreases the growth rate.

Journal ArticleDOI
TL;DR: In this article, the compositional and growth temperature dependences of the cutoff wavelength for epilayers were investigated, and the results showed that the purity of epilayer is considerably improved by doping Gd in the melt.
Abstract: High-quality Ga1-xInxAs1-ySby/InAs with mirror-smooth surfaces were grown at 650-595°C by means of Liquid Phase Epitaxy (LPE). The compositional and growth temperature dependences of the cutoff wavelength for epilayers were investigated. Van der Pauw measurements, optical microscopy, Fourie Transform IR (FTIR) spectroscopy, Electron Probe Microanalysis (EPMA), Secondary Ion Mass Spectroscopy (SIMS) and Photoluminescence (PL) spectroscopy were used to characterize the quality of epilayers. The results show that the purity of epilayers is considerably improved by doping Gd in the melt. Room-temperature electron mobility up to 30000 cm2/(Vs) with carrier density of 5.7×1015 cm-3 and full width at halfmaximum (FWHM) of the PL spectra as narrow as 12.45 meV, which are the best results so far for this material to our knowledge, have been achieved. The cutoff wavelengths of epilayers are between 3.4 and 5.0 mm at room temperature.

Journal ArticleDOI
TL;DR: In this article, the electrical properties of as-grown and annealed (ZnTe) x (CdSe) 1 − x single crystals, prepared by the vapour phase growth technique in the entire range of x in the temperature range 160-400 K are reported for the first time.


Journal ArticleDOI
TL;DR: In this article, the effects of Yb addition to melts used for the growth of InGaAs/InP heterostructures by liquid phase epitaxy were investigated, and the results indicate that impurities in the Yb play an important role in determining the changes in electrical properties observed in the epilayers after Yb treatment of the melt.
Abstract: We have investigated the effects of Yb addition to melts used for the growth of InGaAs/InP heterostructures by liquid phase epitaxy. Our results indicate that impurities in the Yb play an important role in determining the changes in electrical properties observed in the epilayers after Yb treatment of the melt. We have examined samples using double-crystal x-ray diffractometry, photoluminescence, Hall/van der Pauw measurements, and secondary-ion mass spectroscopy. After Yb treatment, the residual carrier concentrations of the epilayers were reduced by more than one order of magnitude and the samples luminesced more strongly; while the lattice matching and crystal quality of the epilayers were not measurably affected by the Yb. There was a smaller-than-expected increase in the 77K mobility and a marked increase in the compensation ratio of the epilayers grown after the addition of Yb to the melt. We believe the Yb is both acting as a scavenging agent in the melt, combining with impurities that otherwise would have been incorporated in the epilayers, and introducing deep level impurities of its own, which are incorporated into the grown layers.

Journal ArticleDOI
TL;DR: In this paper, the authors observed a strong correlation between sheet carrier concentration in Si planar-doped AlInAs layers and the flow rate of AsH3 supplied during the doping.
Abstract: We observed a strong correlation between sheet carrier concentration in Si planar‐doped AlInAs layers and the flow rate of AsH3 supplied during the doping. The AlInAs layers were grown by metalorganic chemical vapor deposition and were planar doped by supplying Si2H6 in AsH3 atmosphere. The sheet carrier concentration measured by the van der Pauw method and the sheet Si atom concentration measured by secondary ion mass spectrometry agreed well. Our results can be interpreted on the basic of a previously introduced model taking into account Si incorporation and desorption. We applied this desorption effect to doping control in Si planar‐doped AlInAs/GaInAs selectively doped heterostructures. By changing AsH3 flow rate at a given doping time and Si2H6 flow rate, we could control the sheet Si atom concentration and hence the two‐dimensional electron gas in the selectively doped heterostructures.

Journal ArticleDOI
TL;DR: In this article, the authors proposed a non-destructive method which allows us to determine the sheet resistance R□, the mobility μ and the density n of the free carriers of semiconducting layers.
Abstract: We propose a novel non-destructive method which allows us to determine the sheet resistance R□ , the mobility μ and the density n of the free carriers of semiconducting layers. Superficial or burried layers can be measured. The sample may be of any shape and, in particular, this method is useful to characterize wafers. The measurement cell consists of two microstrips lines on a flexible duroid substrate. The ends of these lines are covered with a thin insulator layer and act as electrodes. To characterize a sample, the electrodes are simply pressed on it and a measurement of the modulus of the transmission factor between the two lines is performed. Eliminating the scattering factor phase leads to a simplification of the experimental set-up and a lowering of its cost. At the working frequency (1–2 GHz), the impedance values of the capacitive contacts are small with respect to R□ . Therefore, the resistance between the two electrodes and R□ are easily obtained. The determination of μ is achieved from magnetoresistance measurements. Then, the value of n can be calculated if the thickness of the layer is known. The measurement ranges are as follows: 100 Ω k Ω; 2000 cm 2 V −1 s −1 . The accuracy of the results achieved with our method or the van der Pauw method is similar. Lastly, the measurement system is controlled by a microcomputer; thus, the R□, μ and n mapping of a 2 in wafer takes about 1 min per site ( a site corresponds to a tested area with dimensions of about 5 mm × 5 mm ).

Proceedings ArticleDOI
02 Aug 1993
TL;DR: In this paper, the suppression of longitudinal optical phonon (LOP)-electron scattering was sought in multiple quantum well (MQW) structures, and the results of an experiment made elsewhere, which appeared to show the contrary, can be interpreted using arguments other than suppression of electron LOP scattering in MQWs.
Abstract: The suppression of longitudinal optical phonon (LOP)-electron scattering was sought in multiple quantum well (MQW) structures. The structures had GaAs well widths=12, 15 and 20 mono layers (ML) and AlAs barrier widths =2 and 4 ML. The MQWs were grown in the channel of GaAs/Al/sub 0.3/Ga/sub 0.7/As modulation doped field effect transistors (MODFETs) without gates. The Hall mobility and carrier sheet density were measured by the van der Pauw method. The Hall mobility of the MQW samples was found to be less than that of the control samples (without MQW) at room temperature, but was better at temperatures lower than 50 K. The reduction of the room temperature mobility was due to interaction of the well electrons with the interface polaritons from the AlAs barriers. The increase of the low temperature mobility was due to reduced remote ionized impurity scattering of the well electrons. The evidence of performance improvement of MQW devices at room temperature due to suppression of electron-LOP scattering is thus disputed by this study. The results of an experiment made elsewhere, which appeared to show the contrary, can be interpreted using arguments other than the suppression of electron-LOP scattering in MQWs. >

Journal ArticleDOI
TL;DR: In this paper, the effect of thermal processing on self-aligned TiSi2 CMOS structures with phosphorus-doped gates has been investigated in the temperature range of 800-1000 degrees C.
Abstract: The effect of thermal processing on salicided (self-aligned TiSi2) CMOS structures with phosphorus-doped gates has been investigated in the temperature range of 800-1000 degrees C. The salicided layer in the submicrometre structures reported in this paper was formed by rapid thermal processing of the titanium film on doped substrates in a nitrogen ambient. The interface contact resistance as a function of temperature (i.e. TiSi2/Si contact resistance) increases for both n-(As) and p-(BF2) implanted junctions, the increase is greater for the case of p (BF2) junctions. The sheet resistances measured on Van der Pauw patterns (large area) are affected by annealing temperature, time and dopant species, in addition to the substrate microstructure. The BF2-implanted phosphorus-doped polysilicon shows the maximum increase in sheet resistance on Van der Pauw patterns with thermal processing, as compared with any other case. The narrower (1.0 mu m) runners of polysilicon show greater increase in sheet resistances on thermal processing than do large-area Van der Pauw patterns.