Showing papers on "Van der Pauw method published in 1996"
TL;DR: In this paper, the relationship between growth rate of Cu2O film and oxidation temperature is formulated from both optical and Rutherford backscattering measurements, along with a similar relationship for the growth of cupric oxide (CuO).
Abstract: Cuprous oxide ( Cu2O) films are prepared by simple thermal dry oxidation of sputtered Cu films at temperatures lower than 350° C. The relationship between growth rate of Cu2O film and oxidation temperature is formulated from both optical and Rutherford backscattering measurements, along with a similar relationship for the growth of cupric oxide (CuO). Electrical and structural properties of Cu2O films are measured by the van der Pauw and the X-ray diffraction methods respectively. It is found that stable Cu2O films can be obtained under suppression of CuO growth when Cu films are oxidized at about 300° C, and that the Hall mobility of such Cu2O films is relatively high and reaches to several tens cm2/Vs.
54 citations
TL;DR: Low resistivity, p-type, single crystal aluminum nitride-carbon (AlN : C) films were grown by metal organic chemical vapor deposition (MOCVD).
41 citations
TL;DR: In this paper, the sheet resistance of a cross microarea with a size as small as was determined by using a modified van der Pauw method, in which the tip positions of four probes were controlled at the peripheral areas outside a demarcation curve, as shown in the text, by direct inspection through a microscope with a magnification of.
Abstract: The sheet resistance of a cross microarea with a size as small as was determined by using a modified van der Pauw method, in which the tip positions of four probes were controlled at the peripheral areas outside a demarcation curve, as shown in the text, by direct inspection through a microscope with a magnification of . It is not necessary to prepare four metallized electrodes for setting probes. The measurement results are independent of the wanderings of probes and it is unnecessary to determine the precise positions of probes in order to make corrections for the boundary effect. These conclusions have been proved in this paper by using the finite element method (FEM) and have been confirmed by the experimental determination of sheet resistance for several boron-doped cross microareas isolated by p - n junctions on an n-type silicon wafer.
36 citations
TL;DR: The magnetoresistance of single crystals of the quasi-two-dimensional (Q2D) organic conductor has been studied at temperatures between 700 mK and 300 K in magnetic fields of up to 15 T and hydrostatic pressures up to 20 kbar.
Abstract: The magnetoresistance of single crystals of the quasi-two-dimensional (Q2D) organic conductor has been studied at temperatures between 700 mK and 300 K in magnetic fields of up to 15 T and hydrostatic pressures of up to 20 kbar. Measurements of the resistivity using a direct-current van der Pauw technique at ambient pressure show that the material undergoes a metal-to-insulator transition at ; below this temperature the resistivity increases by more than five orders of magnitude as the samples are cooled to 4.2 K. If the current exceeds a critical value, the sample resistivity undergoes irreversible changes, and exhibits non-ohmic behaviour over a wide temperature range. Below 30 K, either an abrupt increase of the resistivity by two orders of magnitude or bistable behaviour is observed, depending on the size and/or direction of the measurement current and the sample history. These experimental data strongly suggest that the metal - insulator transition and complex resistivity behaviour are due to the formation of a charge-density wave (CDW) with a well-developed domain structure. The magnetotransport data recorded under hydrostatic pressure indicate that pressure has the effect of gradually reducing the CDW ordering temperature. At higher pressures, there is a pressure-induced transition from the CDW state to a metallic, superconducting state which occurs in two distinct stages. Firstly, a relatively small number of Q2D carriers are induced, evidence for which is seen in the form of the magnetoresistance and the presence of Shubnikov - de Haas oscillations; in spite of the low carrier density, the material then superconducts below a temperature of . Subsequently, at higher pressures, the CDW state collapses, resulting in Q1D behaviour of the magnetoresistance, and eventual suppression of the superconductivity.
33 citations
TL;DR: In this paper, a combination of atomic force microscopy and van der Pauw measurements is used to investigate and explain the strong influence of the buffer layers on the morphology in the quantum well that is shown to be responsible for the great differences in the observed low-temperature mobilities.
Abstract: The growth of modulation‐doped InAs/(Al,Ga)Sb quantum wells on GaAs substrates employing molecular beam epitaxy requires care in the nucleation and the use of buffer layers to achieve high quality material. Despite a 7% lattice mismatch between the substrate and the active layers, fully relaxed epitaxial growth can be accomplished, and quantum wells with electron sheet concentrations of 7×1012 cm−2 having low‐temperature mobilities as high as 300 000 cm2/V s have been routinely fabricated recently in our laboratory. In the present work the combination of atomic force microscopy and van der Pauw measurements is used to investigate and explain the strong influence of the buffer layers on the morphology in the quantum well that is shown to be responsible for the great differences in the observed low‐temperature mobilities.
33 citations
TL;DR: In this article, a p-type oxide thin film and an n-type thin film, ZnO, were fabricated by a liquid phase method using metal acetates as starting reagents.
Abstract: A p-type oxide thin film, NiO, and an n-type thin film, ZnO, were fabricated by a liquid phase method using metal acetates as starting reagents. Both the films were transparent, uniform in thickness and porous. By repetition of coating of the n- and p-type films a p–n contact was formed. The contact exhibited nonlinear and rectifying I–V characteristics. A Mott-Schottky plot of the p–n contact revealed that the carrier concentration in each film was constant throughout the thickness and the carrier concentration in NiO was much lower than that estimated from the results obtained using the van der Pauw method. The very low carrier concentration may be due to the existence of interface and surface states in the multilayered porous film.
27 citations
21 citations
TL;DR: In this article, the electrical properties of two types of investigated crystals: THM doped by chlorine with and without additional dopants; HPBM (high pressure Bridgman method).
21 citations
TL;DR: In this paper, the effect of macroscopic inhomogeneities on resistivity and Hall angle measurements is studied by calculating weighting functions (the relative effect of perturbations in a local transport property on the measured global average for the object) for cross, cloverleaf, and bar-shaped geometries.
Abstract: The effect of macroscopic inhomogeneities on resistivity and Hall angle measurements is studied by calculating weighting functions (the relative effect of perturbations in a local transport property on the measured global average for the object) for cross, cloverleaf, and bar‐shaped geometries. The ‘‘sweet spot,’’ the region in the center of the object that the measurement effectively samples, is smaller for crosses and cloverleafs than for the circles and squares already studied, and smaller for the cloverleaf than for the corresponding cross. Resistivity measurements for crosses and cloverleafs suffer from singularities and negative weighting, which can be eliminated by averaging two independent resistance measurements, as done in the van der Pauw technique. Resistivity and Hall measurements made on sufficiently narrow bars are shown to effectively sample only the region directly between the voltage probes.
20 citations
04 Jun 1996
TL;DR: In this article, a four-electrode conductance cell designed and used according to the van der Pauw method can be applied for the absolute determination of the electrolytic conductivity of solutions with an accuracy comparable with that of the secondary standards for this quantity.
Abstract: It appears that a four-electrode conductance cell designed and used according to the van der Pauw method can be applied for the absolute determination of the electrolytic conductivity of solutions with an accuracy comparable with that of the secondary standards for this quantity. Therefore there may be a possibility of avoiding the use of those standards in some cases. The results of the experimental investigation of a prototype model of the cell of this type, carried out by the authors, are consistent with the theoretical considerations and computer modeling. An absolute determination of electrolytic conductivity has been made for 0.01 and 0.1 M KCl solutions, with an overall uncertainty lower than 0.4%.
20 citations
TL;DR: In this article, the Van der Pauw technique was used to measure the resistivity of polycrystalline films of CdTe on glass substrates and the behavior was found to fit properly with the Fuchs and Sondheimer relation with parameters ϱ = 4.39 × 10 5 5 Ω cm and l = 734 nm.
TL;DR: In this paper, an n-type WO3 thin film on a p-type GaAs substrate has been investigated in terms of its structural, electrical, and photocurrent-voltage characteristics.
Abstract: An n‐type WO3 thin film on a p‐type GaAs substrate has been investigated in terms of its structural, electrical, and photocurrent–voltage characteristics. Crystallization of the monoclinic phases of WO3 occurred at 400 °C as identified by a glancing angle x‐ray diffractometer. Above 400 °C, small traces of gallium oxide (Ga2O3)were observed along with higher intensities of the monoclinic peaks. The formation of Ga2O3 was confirmed by a depth profile analysis using an Auger electron spectrometer. Electrical resistivity measured by the van der Pauw method was influenced by the crystalline nature and the interfacial states induced by the diffused atoms from each side of WO3 and GaAs. A high photocurrent density of 7.5 mA/ cm2 at −1.0 V (vs SCE) appeared at the crystalline WO3 on p‐type GaAs at 400 °C resulting from effective carrier movement through the interfaces.
TL;DR: In this article, Si is a well behaved p-type dopant in GaSb and Ga0.8In0.2Sb compounds, and the effects of trimethylantimony mole fraction and the growth temperature on the Si incorporation behavior were also studied.
Abstract: p‐type GaSb and Ga0.8In0.2Sb layers were grown on GaAs substrates by the low pressure metalorganic vapor phase epitaxy technique, using silane as the dopant source. It was found that Si is a well behaved p‐type dopant in GaSb and Ga0.8In0.2Sb compounds. Secondary ion mass spectrometry measurements and Van der Pauw Hall measurements indicated that the compensation ratio (defined as Nd/Na) of 2×1018 cm−3 doped p‐type Ga0.8In0.2Sb layer is less than 0.25, whereas the compensation ratio is less than 0.1 for layers doped to <5×1017 cm−3. Control of p‐type doping level in the mid 1016 cm−3–mid 1018 cm−3 range has been demonstrated. The effects of trimethylantimony mole fraction and the growth temperature on the Si incorporation behavior were also studied.
TL;DR: In this paper, the correlation between defects and electrical resistance of conductive layers on CVD the diamond surface was investigated using ESR and van der Pauw methods, an ESR center with g = 2.003, Δ H PP =8 Oe, which is identical to the carbon dangling bonds in non-diamond phase carbon, is highly distributed with a spin density of 10 20 spinscm −3 in the conductive surface layer.
TL;DR: In this paper, a fully automated precise electrical resistance measurement system for more than one sample has been constructed, with a temperature control accuracy of better than 10 mK. The design features of the system with special reference to the low noise switching methods of currents and voltages are described in detail.
Abstract: A fully automated precise electrical resistance measurement system for more than one sample has been constructed. Conventional four‐probe measurements with van der Pauw and Montgomery configurations are possible with this system. Resistance measurements in the range of a few μΩ to a few GΩ are possible for six samples at a time from room temperature down to liquid‐helium or liquid‐nitrogen temperatures with a temperature control accuracy of better than 10 mK. The design features of the system with special reference to the low‐noise switching methods of currents and voltages are described in detail. Precision of the results thus obtained using this system are highlighted for a few superconducting and semiconducting samples.
TL;DR: In this article, a photochromic device with superlattice structure has been fabricated by means of low-pressure organometallic chemical vapour deposition (LPOMCVD) using ZnO films.
Abstract: We have proposed a new photochromic device in which two kinds of transition metal ions are alternatively doped into a host material with a period of a few tens of nanometres [1]. Such a device with superlattice structure has been fabricated by means of low-pressure organometallic chemical vapour deposition (LPOMCVD) [2, 3]. Using LPOMCVD, we succeeded in the preparation of (11 20) orientated ZnO films [4, 5]. Nevertheless, the resultant ZnO fihn exhibited a fairly low resistivity, because of formation of oxygen vacancies. Insulating ZnO films are required as photochromic host materials. Thus, in the work reported in this letter, oxygen gas was introduced into a reaction chamber during the preparation of a ZnO film. The properties of the resultant ZnO films are discussed on the basis of data of X-ray diffraction (XRD) patterns, electric resistivity, absorption spectra and photoluminescence (PL) spectra. Zinc acetate dihydrate (ZnAc) was used as a precursor of Zn source. The LPOMCVD apparatus was the same system used in our previous letter [4]. A reaction chamber was evacuated to 1.0 x 10 -4 Pa then H20 vapour was introduced into the reaction chamber up to 2.7 × 10 -2 or 6.7 × 10 -3 Pa. Furthermore, oxygen gas was introduced into the chamber using a mass flow meter. The total pressure of the reaction chamber was almost unchanged after oxygen gas was introduced into it. ZnO films were deposited on sapphire (01 ]-2) substrates heated at 350°C. The preparation of the ZnO films was carried out at a low sublimation rate, because both (11 20) and ZnO (0002) reflections were observed in an XRD pattern of a ZnO film prepared at a sublimation rate higher than 3 m g h -1 [5]. The preferential orientation of the ZnO film was analysed from rocking curves for (11 20) ZnO reflection; in XRD measurements (CuK~), the angle (2 0) of the Xray detector was fixed to 56.5 °, then the angle (0) of the sample was independently scanned. The thickhess of the film was evaluated by a surface roughness meter (Kosaka SE-30D). Electric resistivity was measured by the Van der Pauw technique. PL spectra were measured using a 50 cm focal length grating monochromator, a lock-in-amplifier and a cw He-Cd laser (325 rim, 10 roW) as an excitor. The conditions for the preparation of ZnO films are listed in Table I. As shown in the results of samples 1 and 4, the deposition rate is not proportional to the sublimation rate alone. The partial pressure of H20 is another factor controlling the deposition rate. As a general tendency, addition of oxygen gas leads to a decrease in the deposition rate, irrespective of the H20 partial pressure. Fig. 1 shows XRD patterns of the ZnO films. Only (11 20) reflections were seen in the XRD patterns for all samples, so that the preferential orientation is not remarkably disturbed by the addition o f oxygen gas. Nevertheless, the intensity of the (11 20) reflection decreases with the flow rate of oxygen gas. As for the samples 1, 2 and 3, the intensity of the (11 20) reflection normalized by the film thickness is decreased by the addition of oxygen gas. In general, orientation of the ZnO film has an influence on the intensity of the XRD patterns. To clarify the relation between orientation and intensity of the ZnO (11 20) reflection, the orientations of these ZnO films were evaluated from rocking curves for the ZnO (11 2_-0) reflections. The rocking curves of the ZnO (11 20) reflections, which are not shown here, have full width at half maximum (FWHM) of 2.8, 3.2, 3.0, 4.2 and 6.1 ° for samples 1, 2, 3, 4 and 5, respectively. The inclination angles of ZnO (1120) plane with respect to A1203 (0224) plane are 2.3, 1.9, 2.4, 2.6 and 1.7 ° for samples 1, 2, 3, 4 and 5, respectively. Except for sample 5, the preferential orientation is not significantly affected by the addition of oxygen gas. Accordingly, the decrease in the intensities of the (1 t 20) reflections caused by introducing oxygen gas is not attributable to degradation of the
08 Apr 1996
TL;DR: In this article, the drift mobility and the Hall mobility in which the scatterings are applied are compared. But the results of measurements of the same layer using the Van der Pauw and Hall bar structure only could be used to obtain proper measurements results.
Abstract: Galvanomagnetic measurements were performed on the square shaped samples after Van der Pauw and on the Hall bar at low electric fields app. 1.5 V/cm and magnetic induction app. 6 kG in order to make a comparison between the theoretical and experimental results of the temperature dependence of mobility and resistivity from 70 K to 300 K. A calculation method was obtained of the drift mobility and the Hall mobility in which the scatterings are applied: on ionized impurities, on polar optical phonons, on acoustic phonons (deformation potential), on acoustic phonons (piezoelectric potential) and on dislocations. The elaborated method transformed to a computer program allows us to fit experimental values of the resistivity and the Hall mobility to those calculated. The fitting procedure makes it possible to characterize the quality of the n-type GaAs MBE layer, i.e. the net electron concentration, whole ionized impurities concentration and dislocation density after Read space charge cylinders model. The calculations together with the measurements allow us to obtain compensation ratio value in the layer, too. The influence of the epitaxial layer thickness on layers measurements accuracy in the case of Van der Pauw square probe was investigated. It was stated that in the layers under 3 micrometer the bulk properties are strongly influenced by both surfaces. The results of measurements of the same layer using the Van der Pauw and the Hall bar structure were compared. It was stated that the Hall bar structure only could be used to obtain proper measurements results.
TL;DR: In this paper, the authors measured the resistivity in vacuum from 77 K to 873 K or 1073 K of Ti34Si23N43 and Ti53N47.
Abstract: We have measured by the four-point probe or Van der Pauw technique the resistivity in vacuum from 77 K to 873 K or 1073 K of Ti34Si23N43 and Ti53N47. These films were reactively sputter-deposited on oxidized silicon wafers, with thickness ranging from 200 nm to 500 nm. The resistivity of the Ti34 Si23N43 films decreases with temperature from 680. μΩcm at 80 K to about 570 μΩcm at 873 K. In contrast, resistivity of our Ti53N47 films rises with temperature, reaching a stable value of 62 μΩcm at above 673 K.
TL;DR: In this paper, the authors developed a two-layer Hall effect measurement concept based on the conventional van der Pauw technique applied to the layer and the substrate separately, and the currentvoltage characteristic of the pn-junction was measured and modeled in the analysis as an ohmic resistor.
Abstract: Epitaxial and implanted layers are generally characterized by Hall effect measurements using a pn-junction as electrical insulation of the layer from the substrate. Due to defects, low doping concentrations or thin layers the resistivity of epitaxial or implanted layers is comparable to the resistivity of the pn-junction and the substrate. This results in inefficient electrical insulation between both regions. To be able to determine the properties of epitaxial or implanted layers even in the case of substantial leakage current we developed a two-layer Hall effect measurement concept. This concept is based on the conventional van der Pauw technique applied to the layer and the substrate separately. In addition the current-voltage characteristic of the pn-junction is measured and modeled in the analysis as an ohmic resistor. This two-layer concept is applied to epitaxial grown SiC and the results are compared with conventional van der Pauw technique. In addition both techniques are compared with the results of capacitance-voltage (CV) measurements and secondary ion mass spectroscopy (SIMS).
TL;DR: In this article, thin films of ZnSexCdS1−x (t ∼ 0.6 μm) over the entire range of x, were deposited on glass substrates at two temperatures, 350 and 470 K, by vacuum evaporation.
Abstract: Thin films of ZnSexCdS1−x (t ∼ 0.6 μm) over the entire range of x, were deposited on glass substrates at two temperatures, Ts (350 and 470 K) by vacuum evaporation. X-ray diffraction studies showed that all the films were polycrystalline in nature. Films prepared at 470 K were nearly stoichiometric. Grain size increased with substrate temperature, Ts. The electrical conductivity and Hall measurements were carried out by d.c. van der Pauw technique. Hall effect studies/hot probe test showed that all the films were of n-type conductivity. Hall mobility increased with Ts. In addition, mobilities increased with temperature in films of all compositions, indicating the dominance of grain-boundary scattering. Grain-boundary potentials were in range 0.03–0.06 eV.
21 Apr 1996
TL;DR: In this article, Hall measurements on InP-based HEMT-type van der Pauw structures without and with downstream PECVD SiN/sub x/ surface passivation were performed.
Abstract: The surface Fermi level of Ga/sub 0.47/In/sub 0.53/As and Al/sub 0.48/In/sub 0.52/As is determined by Hall measurements on InP-based HEMT-type van der Pauw structures without and with downstream PECVD SiN/sub x/ surface passivation. The passivation increases the surface Fermi level towards the conduction band-edge for both semiconductors in particular for low deposition temperatures. While the increase is clearly noticeable on GaInAs it appears less marked on AlInAs. From the finding that the resulting enhancement of carrier density in the GaInAs cap layer does not lower the DC channel resistivity of SiN/sub x/ passivated HEMT devices conclusions can be drawn about the path of the current in the source and drain regions.
26 Mar 1996
TL;DR: To study the mechanical alloying process and the properties of thermoelectric semiconductor with fine dispersed ceramic particles, Bi-Sb alloys with addition of fine BN and ZrO/sub 2/ were prepared by mechanical alloyed and sintered by hot pressing.
Abstract: To study the mechanical alloying process and the properties of thermoelectric semiconductor with fine dispersed ceramic particles, Bi-Sb alloys with addition of fine BN and ZrO/sub 2/ were prepared by mechanical alloying The milled powders were sintered by hot pressing The Bi/sub 925/Sb/sub 75/ solid solution with fine dispersion of BN and ZrO ceramic particles were successfully synthesized The sintered composites show very fine microstructures in which average grain size are less than one micron The thermal properties of composites were measured by laser flash method at room temperature The electrical properties were measured by Van der Pauw method at room temperature and at 77 K The BN addition has obtained larger reduction of thermal conductivity compared to ZrO/sub 2/ The thermal conductivity has been reduced to 20% of the reported value of Bi-Sb single crystal, which achieved with 10 vol% addition of BN
TL;DR: In this paper, deep level centers correlate strongly with the oxygen content in the AlGaAs layer, the PL response of PM-HEMTs, and the electrical performance of the HEMTs.
04 Jun 1996
TL;DR: In this paper, the effect of electrode-electrolyte solution interface (EESI) on electric field distribution and conductance cell constants has been studied and it has been found that the EESI of current carrying electrodes influences cell field distribution.
Abstract: Electric field distribution in impedance cell designed according to the assumptions of van der Pauw method of electrical conductivity measurement has been used. Particularly the effect of electrode-electrolyte solution interface (EESI) on electric field distribution and conductance cell constants has been studied. It has been found that the EESI of current carrying electrodes influences cell field distribution. It has been concluded as well that the potential difference at potential electrodes-being a measure of conductivity of electrolyte solution filling the cell-does not depend on the fact whether EESI exists provided the current electrodes are driven from current source. The results of measurement experiments proving FEM studies are also presented in the paper.
TL;DR: In this paper, the growth of La doped SrTiO3 thin films on MgAl2O4 (100) substrates using the Pulsed Laser Deposition (PLD) technique was analyzed by X-Ray Diffraction and Rutherford Backscattering Spectroscopy (RBS).
08 Apr 1996
TL;DR: In this paper, the lateral resistivity of evaporated CdSe thin films has been measured using the van der Pauw technique, which is useful in the development of inexpensive solar cells based on this material.
Abstract: Thin Films Laboratory, Department of Physics, Keele University, Keele, Staffordshire, ST5 5BG, U.K.ABSTRACTThe lateral resistivity of evaporated CdSe thin films has been measured using the van der Pauw technique. Measurementswere performed as a function of the film thickness, the deposition rate and the substrate temperature during deposition. Suchmeasurements are useful in the context of the development of inexpensive solar cells based on this material. In contrast tosome other cadmium compounds the mean resistivity appeared to increase with increasing thickness, prior to a rapid decreaseat a thickness above about 1 jtm. This effect is thought to be related to the varying composition of the evaporating CdSecharge during the course of the evaporation process. Films deposited at a substrate temperature of 200°C (473 K) showeda rapid increase in resistivity from below 102 c m to above 1 m as the deposition rate increased up to approximately 0.5nm s', while for rates above this value and up to 3 nm s the resistivity remained essentially constant. This behaviour isthought to be related to a decrease in mobility and/or free carrier concentration resulting respectively from increasing grainboundary scattering and trapping effects, as a result of a decrease in the mean grain size with increasing deposition rate.Resistivity was strongly dependent on the substrate temperature during deposition, showing a moderate increase withincreasing temperature up to about 75°C (=
TL;DR: In this article, the conductivity of quasi-2D organic conductor (BEDT-TTF)3Cl2 2H2Os have been investigated at low temperatures in high magnetic fields up to 14 T using Van der Pauw method.
Abstract: The conductivity of quasi-2D organic conductor (BEDT-TTF)3Cl2 2H2Os have been investigated at low temperatures in high magnetic fields up to 14 T using Van der Pauw method. The sample undergoes metal-insulator transition at T ∼ 100 K with the total increase of the resistivity more than five orders of magnitude when the temperature reaches T = 4.2 K. It had been found out that the excess of the critical value by the measuring current induces irreversible changes of the sample conductivity. A wide region of temperature, 30 K ≤ T ≤ 100 K, appears, where the resistivity ρ(T) acquires chaotic behavior. At T < 30 K the abrupt decrease of the conductivity by two orders of magnitude or the bistability of the conductivity in a form of two ρ(T) branches is observed. The model explaining the metal insulator transition and above mentioned anomalies by the charge density wave formation with the well-developed domain structure is proposed.
TL;DR: Microwave rapid thermal annealing has been used to remove the lattice damage caused by nitrogen ion-implantation as well as to activate the dopant in 6H-SiC.
Abstract: Microwave rapid thermal annealing has been utilized to remove the lattice damage caused by nitrogen (N) ion-implantation as well as to activate the dopant in 6H-SiC. Samples were annealed at temperatures as high as 1,400 C, for 10 min. Van der Pauw Hall measurements indicate an implant activation of 36%, which is similar to the value obtained for the conventional furnace annealing at 1,600 C. Good lattice quality restoration was observed in the Rutherford backscattering and photoluminescence spectra.
TL;DR: In this article, the incorporation of phosphorus into silicon from a spin-on dopant layer (SOD) at 400°C was described, and experiments were carried out with SOD films deposited on (100) silicon substrates by using the spinon technique.
Abstract: Incorporation of phosphorus into silicon from a spin-on dopant layer (SOD) at 400 °C is described. Annealing experiments were carried out with SOD films deposited on (100) silicon substrates by using the spin-on technique. Conventional heating on a hotplate in normal atmosphere and a temperature range up to 400 °C was used to study the dopant incorporation. After removing the SOD-films one part of the silicon substrates was annealed at higher temperatures. Investigations were carried out by SIMS, SAM, XPS, HTEM, stripping Hall and Van der Pauw measurements before and after the high temperature annealing. Chemical phosphorus concentration profiles obtained from low temperature annealed samples showed diffusion depths of 60–80 nm (extrapolated to a substrate doping level of 1016 cm-3) and surface concentrations of 1019–1020 cm-3. Electron concentration profiles exhibiting maximum values around 2⋅1019 cm-3 could be measured on high temperature annealed samples only.
TL;DR: In this paper, two-dimensional electron gases (2DEGs) are grown on GaAs substrates by molecular beam epitaxy (MBE) with various thicknesses of GaAs buffer layers.
Abstract: AlGaAs/GaAs two-dimensional electron gases (2DEGs) are grown on GaAs substrates by molecular beam epitaxy (MBE) with various thicknesses of GaAs buffer layers. Prior to the growth, the substrates are cleaned using an electron cyclotron resonance (ECR) hydrogen plasma at low temperatures where native oxides are not removed from the surface by heating alone. The electrical properties of 2DEGs are evaluated using van der Pauw and Hall effect measurements. The sheet carrier densities and electron mobilities of the plasma-cleaned samples with more than 20-nm-thick buffer layers exhibit almost the same properties as the sample with a 600-nm-thick buffer layer at 77 K. ECR hydrogen plasma cleaning is found to be a promising technique for the regrowth process.