scispace - formally typeset
Search or ask a question

Showing papers on "Silicon carbide published in 1994"


Patent
01 Nov 1994
TL;DR: In this article, a transition crystal structure for providing a good lattice and thermal match between a layer of single crystal silicon carbide and a single crystal gallium nitride was disclosed.
Abstract: A transition crystal structure is disclosed for providing a good lattice and thermal match between a layer of single crystal silicon carbide (25) and a layer of single crystal gallium nitride (24). The transition structure comprises a buffer formed of a first layer of gallium nitride and aluminum nitride (22), and a second layer of gallium nitride and aluminum nitride (23) adjacent to the first layer. The mole percentage of aluminum nitride in the second layer (23) is substantially different from the mole percentage of aluminum nitride in the first layer (22). A layer of single crystal gallium nitride (24) is formed upon the second layer of gallium nitride and aluminum nitride. In preferred embodiments, the buffer further comprises an epitaxial layer of aluminum nitride upon a silicon carbide substrate.

499 citations


Journal ArticleDOI
TL;DR: In this article, a site-competition epitaxy (SCE) was proposed for the chemical vapor deposition of 6H-SiC epilayers on commercially available (0001)SiC silicon-face substrates.
Abstract: We present and discuss a novel dopant control technique for compound semiconductors, called site‐competition epitaxy, which enables a much wider range of reproducible doping control and affords much higher and lower epilayer doping concentrations than was previously possible. Site‐competition epitaxy is presented for the chemical vapor deposition of 6H‐SiC epilayers on commercially available (0001)SiC silicon‐face substrates. Results from utilizing site‐competition epitaxy include the production of degenerately doped SiC epilayers for ohmic‐as‐deposited (i.e., unannealed) metal contacts as well as very low doped epilayers for electronic devices exhibiting SiC record‐breaking reverse voltages of 300 and 2000 V for 3C‐ and 6H‐SiC p‐n junction diodes, respectively.

300 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that micropipe defects originating in 4H- and 6H-SiC substrates can cause pre-avalanche reverse bias point failures in most epitaxially-grown pn junction devices of 1 mm/sup 2/ or larger in area.
Abstract: Reports on the characteristics of a major defect in mass-produced silicon carbide wafers which severely limits the performance of silicon carbide power devices. Micropipe defects originating in 4H- and 6H-SiC substrates were found to cause pre-avalanche reverse-bias point failures in most epitaxially-grown pn junction devices of 1 mm/sup 2/ or larger in area. Until such defects are significantly reduced from their present density (on the order of 100's of micropipes/cm/sup 2/), silicon carbide power device ratings will be restricted to around several amps or less. >

287 citations


Patent
12 Aug 1994
TL;DR: A light emitting diode that emits in the green portion of the visible spectrum, along with a method of producing the diode was disclosed in this article, where a 6H silicon carbide substrate having a planar surface inclined more than one degree off axis toward one of the directions was used.
Abstract: A light emitting diode is disclosed that emits in the green portion of the visible spectrum, along with a method of producing the diode The light emitting diode comprises a 6H silicon carbide substrate having a planar surface inclined more than one degree off axis toward one of the directions; an ohmic contact to the substrate; a first epitaxial layer of 6H silicon carbide on the inclined surface of the substrate and having a first conductivity type; a second epitaxial layer of 6H silicon carbide on the first layer and having the opposite conductivity type for forming a p-n junction between the first and second layers; and an ohmic contact to the second epitaxial layer The diode produces a peak wavelength of between about 525 and 535 nanometers with a spectral half width of no more than about 90 nanometers

227 citations


Patent
20 Sep 1994
TL;DR: In this paper, a Group III nitride laser structure is disclosed with an active layer that includes at least one layer of a GroupIII nitride, a silicon carbide substrate, and a buffer layer between the active layer and the substrate.
Abstract: A Group III nitride laser structure is disclosed with an active layer that includes at least one layer of a Group III nitride or an alloy of silicon carbide with a Group III nitride, a silicon carbide substrate, and a buffer layer between the active layer and the silicon carbide substrate. The buffer layer is selected from the group consisting of gallium nitride, aluminum nitride, indium nitride, ternary Group III nitrides having the formula A x B 1-x N, where A and B are Group III elements and where x is zero, one, or a fraction between zero and one, and alloys of silicon carbide with such ternary Group III nitrides. In preferred embodiments, the laser structure includes a strain-minimizing contact layer above the active layer that has a lattice constant substantially the same as the buffer layer.

190 citations


Journal ArticleDOI
01 Jan 1994-Nature
TL;DR: In this paper, the authors reported that silicon carbide, the most common component of composite ceramics, can be coated with carbon films of nanometre to micrometre thickness by hydrothermal treatment at 300-800 °C.
Abstract: CARBON films find applications in a wide range of fields, ranging from microelectronics to materials science1. In ceramic matrix composites they confer the high strength and toughness needed for applications in aerospace, nuclear and automotive engineering2. Chemical vapour deposition is traditionally used to prepare carbon films, but it is relatively expensive, and not easily adapted to coating samples in the form of whiskers, platelets or powders. Here we report that silicon carbide, the most common component of composite ceramics, can be coated with carbon films of nanometre to micrometre thickness by hydrothermal treatment at 300–800 °C. We have applied the technique to SiC fibres, powders, platelets and single crystals, as well as to other carbides. Our method should provide a general and inexpensive route to high-toughness composites and lubricating coatings.

185 citations


Journal ArticleDOI
TL;DR: The plane-wave pseudopotential approach to density-functional theory (DFT) in the local-density approximation has been applied to investigate a variety of ground-state properties of the 3C, 2H, and 4H polytypes of silicon carbide to obtain lattice-dynamical properties of cubic SiC such as the phonon-dispersion curves.
Abstract: The plane-wave pseudopotential approach to density-functional theory (DFT) in the local-density approximation has been applied to investigate a variety of ground-state properties of the 3C, 2H, and 4H polytypes of silicon carbide. The linear-response theory within DFT has been used to obtain lattice-dynamical properties of cubic SiC such as the phonon-dispersion curves, phonon eigenvectors, elastic and Gr\"uneisen constants, as well as the thermal expansion coefficient and specific heat within the quasiharmonic approximation. Finally, we present some results for phonon-dispersion curves in the hexagonal 2H (wurtzite) and 4H structure. These results are analyzed and discussed in view of further applications to temperature-dependent properties.

180 citations


Patent
19 Dec 1994
TL;DR: In this paper, a three-terminal interconnected silicon MOSFET and silicon carbide MESFET (or JFET) was designed to block positive drain biases when the gate electrode is shorted to the source electrode.
Abstract: A silicon carbide switching device includes a three-terminal interconnected silicon MOSFET and silicon carbide MESFET (or JFET) in a composite substrate of silicon and silicon carbide. For three terminal operation, the gate electrode of the silicon carbide MESFET is electrically shorted to the source region of the silicon MOSFET, and the source region of the silicon carbide MESFET is electrically connected to the drain of the silicon MOSFET in the composite substrate. Accordingly, three-terminal control is provided by the source and gate electrode of the silicon MOSFET and the drain of the silicon carbide MESFET (or JFET). The switching device is designed to be normally-off and therefore blocks positive drain biases when the MOSFET gate electrode is shorted to the source electrode. At low drain biases, blocking is provided by the MOSFET, which has a nonconductive silicon active region. Higher drain biases are supported by the formation of a depletion region in the silicon carbide MESFET (or JFET). To turn-on the device, the gate electrode is biased positive and an inversion layer channel of relatively low resistance is formed in the silicon active region. The channel electrically connects the source of the silicon carbide MESFET (or JFET) with the source of the silicon MOSFET to thereby turn-on the device when a positive drain bias is applied.

159 citations


Journal ArticleDOI
01 May 1994-Wear
TL;DR: In this article, a theoretical model for estimating the abrasive wear resistance of multiphase materials and composites from the wear resistances of the constituents is proposed, and two rules for the dependence of the amount of reinforcing phase, corresponding to two wear modes are derived.

138 citations


Journal ArticleDOI
TL;DR: In this article, the Raman frequencies increase with increasing pressures and a very interesting turnaround in the LO-TO splitting is observed above 60 GPa. But the SiC is transparent to the visible light at 95 GPa and the anticipated metallic phase was not observed.
Abstract: We report the Raman study on $6H$-SiC to ultrahigh pressure of 95 GPa in a diamond anvil cell. The $\mathrm{LO}(\ensuremath{\Gamma})$ and $\mathrm{TO}(\ensuremath{\Gamma})$ Raman frequencies increase with increasing pressures. A very interesting turnaround in the LO-TO splitting is observed above 60 GPa. The density variation of the mode Gr\"uneisen parameters for $6H$-SiC is compared to that of silicon, cubic boron nitride, and diamond. The SiC is transparent to the visible light at 95 GPa and the anticipated metallic phase was not observed.

113 citations


Patent
09 Dec 1994
TL;DR: In this article, a method of obtaining high quality passivation layers on silicon carbide surfaces by oxidizing a sacrificial layer of a silicon-containing material on the silicon-carbide portion of a device structure was proposed, which is substantially free of dopants that would degrade the electrical integrity of the oxide layer.
Abstract: A method of obtaining high quality passivation layers on silicon carbide surfaces by oxidizing a sacrificial layer of a silicon-containing material on a silicon carbide portion of a device structure to substantially consume the sacrificial layer to produce an oxide passivation layer on the silicon carbide portion that is substantially free of dopants that would otherwise degrade the electrical integrity of the oxide layer.

Journal ArticleDOI
01 Aug 1994
TL;DR: The development of power semiconductor devices with MOS-gate structures has enabled the control of large amounts of energy with very little input power as mentioned in this paper, which is the driving force for enhancement of the performance of variable-frequency motor drives.
Abstract: Advances in power semiconductor technology are the driving force for enhancement of the performance of variable-frequency motor drives. The development of power semiconductor devices with MOS-gate structures has enabled the control of large amounts of energy with very little input power. An equally important advancement has taken place in the development of improved rectifiers with reduced losses for high-frequency operation. In addition, the advent of MOS-gated power switches has led to the creation of smart power technology which makes compact systems with built-in diagnostic and protection functions commercially feasible. Although the power semiconductor chips are all made from silicon today, recent analysis has indicated that devices fabricated from silicon carbide have the potential for completely displacing silicon devices in the long range. >

Journal ArticleDOI
Abstract: In this letter we report on the fabrication and initial electrical characterization of the first silicon carbide diodes to demonstrate rectification to reverse voltages in excess of 2000 V at room temperature. The mesa structured 6H‐SiC p+n junction diodes were fabricated in 6H‐SiC epilayers grown by atmospheric pressure chemical vapor deposition on commercially available 6H‐SiC wafers. The devices were characterized while immersed in FluorinertTM to prevent arcing which occurs when air breaks down under high electric fields. The simple nonoptimized diodes, whose device areas ranged from 7×10−6 to 4×10−4 cm2, exhibited a 2000 V functional device yield in excess of 50%.

Journal ArticleDOI
TL;DR: In this paper, a simple edge termination is described which can achieve near ideal parallel plane breakdown for silicon carbide devices, which involves self aligned implantation of a neutral species on the edges of devices to form an amorphous layer.
Abstract: In this paper, a simple edge termination is described which can achieve near ideal parallel plane breakdown for silicon carbide devices. This novel edge termination involves self aligned implantation of a neutral species on the edges of devices to form an amorphous layer. With this termination formed using argon implantation, the breakdown voltage of Schottky barrier diodes was measured to be very close to ideal plane parallel breakdown voltage. >

Journal ArticleDOI
TL;DR: In this paper, a method to produce SiC whiskers without the presence of metal catalysts by reacting carbon nanoclusters with SiO at 1700°C was reported, and electron diffraction and EDX confirm that the product is SiC with a single crystalline hexagonal phase.

Journal ArticleDOI
TL;DR: Hall effect measurements in a Hall-bar configuration are performed on nitrogen-doped n-type bulk 4H, 6H, and 15R SiC single crystals cut into small parallelepipeds with their longest edges either parallel or perpendicular to the c axis.
Abstract: Hall effect measurements in a Hall‐bar configuration are performed on nitrogen‐doped n‐type bulk 4H, 6H, and 15R SiC single crystals cut into small parallelepipeds with their longest edges either parallel or perpendicular to the c axis. In the temperature range investigated (40–700 K), an anisotropy of the electron Hall mobility is observed in all three polytypes. While the mobility perpendicular to the c axis—with magnetic field perpendicular or parallel to the c axis—is greater than the mobility parallel to the c axis for 6H and 15R SiC, 4H SiC shows the opposite behavior.

Journal ArticleDOI
TL;DR: In this paper, a Fowler-Nordheim-type current conduction mechanism with a barrier height of 2.7 eV between silicon carbide and oxide was found for the Si face of 6H-silicon carbide.
Abstract: Measurement of current conduction in the metal/thermal oxide/n‐type 6H‐silicon carbide is reported. The thermal oxides were grown on nitrogen‐doped n‐type 6H‐silicon carbide at 1275 °C in a dry oxygen ambient. Analysis indicates a Fowler–Nordheim type current conduction mechanism with a barrier height of 2.7 eV between silicon carbide and oxide. Using this value an electron affinity of 3.7–3.8 eV was determined for the Si face of 6H‐silicon carbide. The breakdown field strength for the oxides grown on n‐type 6H‐silicon carbide was 10 MV/cm which is comparable to the breakdown field strength of thermal oxides grown on silicon. Capacitance‐voltage measurements indicated that the interface between n‐type silicon carbide and the thermally grown oxide has a low (5×1010 cm−2 eV−1) interface trap density (Dit). The effective charge density in the oxide was estimated to be 1×1011 cm−2. These measurements indicate that the quality of oxides thermally grown on 6H‐silicon carbide is comparable to those grown on silicon.


Patent
18 Nov 1994
TL;DR: In this article, a method for making a composite ceramic article by infiltration of a sintered ceramic preform with an infiltrate phase is presented, where a silicon carbide preform is first infiltrated with carbon to coat the lamelli of the preform, then the carbon is infiltrated with molten silicon, whereby the molten silicon and carbon react to form silicon carbides in the interlamellar regions.
Abstract: A method for making a composite ceramic article by infiltration of a sintered ceramic preform with an infiltrate phase. The ceramic preform is made by directionally solidifying a liquid medium containing a dispersion of ceramic particles to produce a green, porous ceramic preform a plurality of interconnected lamelli that are partially separated from one another by complementary interlamellar regions, removing the solidified liquid medium and sintering the ceramic preform. This method may be used to make silicon carbide composites where a silicon carbide preform is first infiltrated with carbon to coat the lamelli of the preform, followed by infiltration of the carbon coated preform with molten silicon, whereby the molten silicon and carbon react to form silicon carbide in the interlamellar regions. The ceramic preform may also be coated with a thin, diffusion-inhibiting ceramic layer prior to infiltration in order to prevent interdiffusion between the lamelli of the preform and the infiltrate phase, and provide a plurality of mechanically weak, crack deflecting interfaces within the composite article.

Patent
30 Nov 1994
TL;DR: In this paper, a method for producing epitaxial layers of silicon carbide that are substantially free of micropipe defects is described. But the method is not suitable for the fabrication of high-level structures.
Abstract: A method is disclosed for producing epitaxial layers of silicon carbide that are substantially free of micropipe defects. The method comprises growing an epitaxial layer of silicon carbide on a silicon carbide substrate by liquid phase epitaxy from a melt of silicon carbide in silicon and an element that enhances the solubility of silicon carbide in the melt. The atomic percentage of that element predominates over the atomic percentage of silicon in the melt. Micropipe defects propagated by the substrate into the epitaxial layer are closed by continuing to grow the epitaxial layer under the proper conditions until the epitaxial layer has a thickness at which micropipe defects present in the substrate are substantially no longer reproduced in the epitaxial layer, and the number of micropipe defects in the epitaxial layer is substantially reduced.

Journal ArticleDOI
01 Apr 1994-Nature
TL;DR: In this article, the use of an aromatic species (xylene) as the source of carbon during deposition results in a form of amorphous silicon carbide that exhibits strong blue luminescence.
Abstract: THE development of new electroluminescent materials is of current technological interest for use in flat-screen full-colour displays1. For such applications, amorphous inorganic semiconductors appear particularly promising, in view of the ease with which uniform films with good mechanical and electronic properties can be deposited over large areas2. Luminescence has been reported1 in the red-green part of the spectrum from amorphous silicon carbide prepared from gas-phase mixtures of silane and a carbon-containing species (usually methane or ethylene). But it is not possible to achieve blue luminescence by this approach. Here we show that the use of an aromatic species—xylene—as the source of carbon during deposition results in a form of amorphous silicon carbide that exhibits strong blue luminescence. The underlying structure of this material seems to be an unusual combination of an inorganic silicon carbide lattice with a substantial 'organic' π-conjugated carbon system, the latter dominating the emission properties. Moreover, the material can be readily doped with an electron acceptor in a manner similar to organic semiconductors3, and might therefore find applications as a conductivity- or colour-based chemical sensor.

Journal ArticleDOI
TL;DR: In this article, a synergistic effect by fine SiC dispersoids operating on the submicrometer scale is examined for enhancing the deformation and fracture properties of Si3N4 ceramics.
Abstract: The hypothesis that a synergistic effect by fine SiC dispersoids operating on the submicrometer scale is capable of enhancing the deformation and fracture properties of Si3N4 ceramics has been examined. In order to single out the effect of the SiC dispersion from other microstructural factors affecting the material properties, experiments were conducted on a highly pure and dense Si3N4 material, suitable for basic investigations. Fracture mechanics and creep characterizations were performed at room temperature and at 1400°C on composites containing 25 vol% submicrometer SiC particles, for which the intragranular fraction was varied by changing the sintering conditions. Despite the obtained difference in composite microstructure, almost no improvement in either the fracture toughness or strength, as compared with the monolithic material, was found. Similarly, the slow crack growth and creep resistance at 1400°C were still dictated by the inherent properties of the matrix. This study emphasizes the need for scientific rather than empirical approaches on simple systems, before deducing general rules for the microstructural design of structural ceramics.

Journal ArticleDOI
TL;DR: In this paper, the energy distribution of trap time constants, capture cross sections, and interface state density of metaloxide-semiconductor (MOS) capacitors made on silicon carbide material was analyzed.
Abstract: Low‐frequency capacitance and conductance measurements have been extensively performed from 1 Hz to 100 kHz and in the 293–673 K temperature range, on metal‐oxide‐semiconductor (MOS) capacitors made on silicon carbide material. The energy distribution of the trap time constants, capture cross sections, and interface‐state density are presented. It is shown that only low‐frequency and high‐temperature measurements may provide the ability to scan the midgap region of the forbidden band gap. The experimental results fully confirm the feasibility of MOS devices on silicon carbide material. Furthermore, conductance measurements at high temperature indicate the presence of deep bulk levels.

Journal ArticleDOI
TL;DR: In this article, the mechanism of self-propagating high-temperature synthesis (SHS) or combustion synthesis of SiC has been investigated using pellets consisting of silicon and carbon powders.
Abstract: The mechanism of self‐propagating high‐temperature synthesis (SHS) or combustion synthesis of SiC has been investigated using pellets consisting of silicon and carbon powders The combustion reaction was initiated by rapidly heating the pellet on a graphite strip The reaction products were analyzed using scanning and transmission electron microscopy, x‐ray diffraction, and Raman spectroscopy The results show that it is possible to produce β‐SiC without any residual silicon and carbon Occasionally, a very small number density of α‐SiC precipitates embedded in the β‐SiC matrix was observed Based upon the microstructural features, it is proposed that the formation of SiC involves the dissolution of carbon into liquid silicon, diffusion of C into liquid silicon, and subsequent precipitation of SiC The size of the SiC crystallites is determined by the diffusion coefficient of carbon in liquid silicon and the time available for SiC precipitation The activation enthalpy for the SHS process is estimated to

Journal ArticleDOI
TL;DR: In this paper, the problem of interfacial reaction in the SiC-Al system can be solved by adding elemental silicon to the matrix to achieve the eutectic composition.
Abstract: The technological process used for the production and processing of metal matrix composites (MMCs) can require contact over extended periods of time between matrix and the ceramic reinforcement or at least the permanence at high temperature and pressure of the two parts in contact. During the contact a chemical interaction takes place in the interfacial zone as a consequence of the free-energy difference existing between ceramic compound and metal. Aluminium and aluminium alloys reinforced with silicon carbide are widely utilized materials. The chemical interaction between matrix and reinforcement is not very fast but the reaction equally occurs, and a harmful layer of interfacial compound (Al4C3) is developed after a sufficiently long time. At present, the degradation of the reinforcement produced by molten matrix is the major problem for some production technologies. This problem has only been solved partially by using a coating or changing the chemical nature of the matrix. In particular, the technological problem of interfacial reaction in the SiC-Al system can be solved by adding elemental silicon to the matrix to achieve the eutectic composition. However, this expedient gives rise to a consequent significant lowering of the melting point. The problem can be overcome and the production process improved without changing the characteristics of the material by the control of processing parameters. The interfacial reaction also produces elementary silicon and this has been found as aluminium-silicon eutectic segregated at the aluminium grain boundary. An accurate description of the kinetic process can be obtained by determining the silicon content present in the matrix by original derivations obtained by means of calorimetric analysis.

Journal ArticleDOI
TL;DR: In this article, the damping capacity of stir-cast aluminium-matrix composites containing graphite and silicon carbide particles, were studied using a cantilever beam specimen and an HP 5423A Structural Dynamics Analyser.
Abstract: The damping capacity of stir-cast aluminium-matrix composites containing graphite and silicon carbide particles, were studied using a cantilever beam specimen and an HP 5423A Structural Dynamics Analyser. Damping data were determined in the first mode of vibration. Aluminium-matrix composites containing 5–10 vol % graphite particles and 10 vol % silicon carbide particles were prepared by the stir-casting technique and die cast to obtain standard samples (6 mm×25 mm100 mm). Graphite particles were found to be more effective in enhancing the damping capacity of composites compared to silicon carbide particles. The damping capacity of composites increased with the volume percentage of graphite within the range studied. However, no notable improvements in damping capacity were observed by dispersion of silicon carbide in aluminium alloy. The results have been analysed in terms of the effect of size, shape, nature and volume fraction of particles on the damping capacity of the aluminium matrix particulate composites and compared with the damping capacity data available in the literature. The effects of frequency, strain amplitude, temperature and processing on damping capacity of the aluminium matrix composites are reviewed.

Journal ArticleDOI
TL;DR: In this article, an Activated Carbon Fiber (ACF) was reacted with gaseous silicon monoxide and was converted to SiC fiber at elevated temperatures as low as 1,473 K. The SiC crystal size in the reacted fiber was approximately 30 nm.
Abstract: Crystalline silicon carbide (SiC) fiber was produced by a new, simple procedure. Activated carbon fiber (ACF) was reacted with gaseous silicon monoxide and was converted to SiC fiber at elevated temperatures as low as 1,473 K. The reacted fiber consisted of submicrometer particles which were not observed in the original ACF. The SiC crystal size in the reacted fiber was approximately 30 nm. The microstructure of the fiber became dense after it was heat-treated in air at 1,573 K or nitrogen gas at 1,873 K.

Patent
18 Feb 1994
TL;DR: A silicon carbide photodiode exhibiting high short-wavelength sensitivity, particularly in the ultraviolet spectrum, and very low reverse leakage current includes a p type conductivity 6H crystalline substrate.
Abstract: A silicon carbide photodiode exhibiting high short-wavelength sensitivity, particularly in the ultraviolet spectrum, and very low reverse leakage current includes a p type conductivity 6H crystalline substrate. A first p- silicon carbide crystalline layer is epitaxially grown on the body. A second n+ silicon carbide crystalline layer is epitaxially grown on the first layer and forms a p-/n+ junction with the first layer. A metallic upper contact layer is formed on a predetermined surface region of the second layer oppositely situated from the junction. The second layer is of a uniform minimum thickness, generally less than 1000 Angstroms, with a greater thickness, typically 3000-4000 Angstroms, beneath the predetermined surface region. The thicker portion of the second layer occupies less than 10% and generally less than 1% of the total second layer surface area. Hence optical sensitivity of the photodiode is essentially determined by the thinner portion of the second layer, while the thicker portion of this layer is made sufficiently large to prevent diffusion of upper contact layer metal into the vicinity of the junction during contact sintering or alloying operations.

Journal ArticleDOI
TL;DR: In this article, the dielectric strength of oxide layers formed by thermal oxidation of silicon carbide (SiC) was investigated using metaloxide-semiconductor capacitors and was found to be tightly bound to 10 MV/cm for oxide thicknesses around 65 nm.
Abstract: This work reports on the dielectric strength of oxide layers formed by thermal oxidation of silicon carbide (SiC). SiC epilayers grown homoepitaxially on the silicon face of 6H‐SiC and 4H‐SiC substrates were oxidized in dry or wet ambient at 1100 °C. The dielectric strength was investigated using metal–oxide‐semiconductor capacitors and was found to be tightly bound to 10 MV/cm for oxide thicknesses around 65 nm and independent of the SiC polytype and substrate doping. Considering the current‐voltage characteristics in the prebreakdown region, dry oxides exhibit superior quality. Fowler–Nordheim tunneling was identified as the limiting current mechanism in the dry oxides. The corresponding barrier heights between the two SiC polytypes and thermal silicon dioxide were determined.

Journal ArticleDOI
TL;DR: In this paper, a self-selective growth of crystalline cubic (/spl beta/) SiC was obtained by propane carbonization of the Si substrate in regions unprotected by an SiO/sub 2/layer, producing planar diodes.
Abstract: SiC/Si heterojunction diodes have been fabricated by two different rapid thermal chemical vapor deposition (RTCVD) processes: a localized self-selective growth and blanket growth. The self-selective growth of crystalline cubic (/spl beta/) SiC was obtained by propane carbonization of the Si substrate in regions unprotected by an SiO/sub 2/ layer, producing planar diodes. Mesa diodes were fabricated using the blanket growth of polycrystalline /spl beta/-SiC produced by the decomposition of methylsilane (CH/sub 3/SiH/sub 3/). The SiC/Si heterojunction diodes show good rectifying properties for both device structures. Reverse breakdown voltage of 50 V was obtained with the self-selective SiC/Si diode. The mesa diodes exhibited even higher breakdown voltages (V/sub br/) of 150 V and excellent ideality factors of 1.06 at 25/spl deg/C. The high V/sub br/ and good forward rectifying characteristics indicate that the SiC/Si heterojunction diode represents a promising approach for the fabrication of wide-gap emitter SiC/Si heterojunction bipolar transistors. >