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Showing papers on "Pulsed laser deposition published in 1988"


Journal ArticleDOI
TL;DR: In this paper, the angular distribution of the composition and thickness of the Y•Ba•Cu oxide film deposited by firing excimer laser (30 ns, 248 nm) pulses at a stoichiometric Y1Ba2Cu3O7−x pellet was measured using Rutherford backscattering technique.
Abstract: Using Rutherford backscattering technique, we have measured the angular distribution of the composition and thickness of the Y‐Ba‐Cu oxide film deposited by firing excimer laser (30 ns, 248 nm) pulses at a stoichiometric Y1Ba2Cu3O7−x pellet. The angular distribution consisted of two distinct components: one a cos θ component, a result of evaporation, and the other a highly forward directed component, a result of a secondary ejection process. The evaporated component is nonstoichiometric, as one would expect, whereas the forward‐directed component has a composition close to that of the pellet. Further, the forward‐directed stoichiometric component increases with the laser energy density in comparison with the evaporated component. These observations are discussed in the context of current models of laser‐induced material ejection at surfaces.The laser energy dependence of the deposition is of critical importance in controlling the film stoichiometry.

357 citations


Journal ArticleDOI
TL;DR: In this paper, the authors classify thin-film deposition by laser evaporation into equilibrium and none-quilibrium processes according to the ways in which the source materials are vaporized.
Abstract: Among the various material growth techniques, physical vapor deposition of thin films encompasses many experimental forms. They can be categorized into equilibrium and none-quilibrium processes according to the ways in which the source materials are vaporized. Equilibrium process is typified by thermal evaporation including the conventional resistive heating, the more elaborate e-beam evaporation. as well as molecular beam epitaxy (MBE). Nonequilibrium processes include sputtering and many of its derivative forms such as ion beam deposition. In comparison with these techniques, thin-film deposition by laser evaporation is less well known and does not fall cleanly into either category. Depending on the laserconditions, the evaporation process can be either thermal, nonthermal, or a mixture of the two.

322 citations


Journal ArticleDOI
TL;DR: In this article, the authors presented reproducibly fabricated high Tc superconducting Y1Ba2Cu3O7−x films with zero-resistance temperatures of ∼89 K and critical current densities about 0.7×106 A/cm2 at 77 K using pulsed laser deposition.
Abstract: 2000 A as‐deposited high Tc superconducting Y1Ba2Cu3O7−x films with zero‐resistance temperatures of ∼89 K and critical current densities about 0.7×106 A/cm2 at 77 K have been reproducibly fabricated at a substrate holder temperature of 650 °C, using pulsed laser deposition, with no post‐annealing. One key to these results is the injection of gaseous oxygen into the laser‐produced plume just in front of the target. In this way, the correct amount of oxygen is incorporated into the as‐grown film so that post‐deposition treatment becomes unnecessary. The in situ growth of such high Tc and Jc films is an important step in the use of the laser deposition technique to fabricate multilayer structures such as Josephson junctions.

252 citations


Journal ArticleDOI
TL;DR: In this article, thin superconducting films of Y•Ba•Cu•O were prepared at 650°C using the pulsed laser deposition technique and they exhibited superconductivity with zero resistance at temperatures as high as 83 K.
Abstract: Thin superconducting films of Y‐Ba‐Cu‐O were prepared at 650 °C using the pulsed laser deposition technique. The as‐deposited films were fully superconducting at low temperature (30 K). After annealing in oxygen at 450 °C for 3 h, the films exhibited superconductivity with zero resistance at temperatures as high as 83 K. Film‐substrate interface reaction was minimal as revealed by Rutherford backscattering and Auger electron spectrometry. These films processed at such low temperatures are also found to have excellent planar surface morphology and high critical current density.

228 citations


Journal ArticleDOI
TL;DR: In this paper, the laser-induced forward transfer technique in which material is ablatively transferred from a thin film to a target substrate by a pulsed excimer laser has been extended to 532 nm using a frequency-doubled YAG laser.
Abstract: The laser‐induced forward transfer technique in which material is ablatively transferred from a thin film to a target substrate by a pulsed excimer laser has been extended to 532 nm using a frequency‐doubled YAG laser. Cu and Ag have been deposited on fused silica substrates using microscope objectives for focusing, resulting in reductions in feature size over that obtainable with the multimode excimer laser. The photothermal deposition process has been modeled using the one‐dimensional thermal diffusion equation, including a moving solid‐melt boundary, with good agreement between theoretical and experimental results.

170 citations


Journal ArticleDOI
TL;DR: In this article, x-ray absorption measurements on films deposited onto substrates at room temperature were performed in order to identify the presence of short-range crystalline order in the films and to rule out the ejection of stoichiometric clusters of material from the pellet during the laser ablation/deposition process instead, binary and ternary suboxides are emitted from the targe.
Abstract: The pulsed laser thin‐film deposition process can enable preparation of thin films of complex composition with good control over the film stoichiometry The film compositions are similar to that of the target pellet and as a consequence this technique appears to be an ideal method for preparing high Tc thin films on a variety of substratesThe factors which contribute to this beneficial phenomenon have been explored by a laser ionization mass spectrometry (LIMS) and a post ablation ionization (PAI) neutral velocity analysis technique in order to determine the mass and velocities of the laser ejected material In addition, x‐ray absorption measurements on films deposited onto substrates at room temperature were performed in order to identify the presence of short‐range crystalline order in the films Both of these studies rule out the ejection of stoichiometric clusters of material from the pellet during the laser ablation/deposition process Instead, binary and ternary suboxides are emitted from the targe

122 citations


Book
01 Jan 1988
TL;DR: The ionized cluster beam (ICB) deposition and epitaxial process is an ion-assisted technique by which high quality films of metals, dielectrics and active semiconductor materials can be formed at a low substrate temperature in a technical-grade vacuum system as discussed by the authors.
Abstract: The ionized cluster beam (ICB) deposition and epitaxial process is an ion-assisted technique by which high quality films of metals, dielectrics and active semiconductor materials can be formed at a low substrate temperature in a technical-grade vacuum system. In the ICB process, film material is vaporized from a confinement crucible under conditions which result in the formation of aggregate clusters of atoms held together by weak forces. Clusters can be ionized by electron impact and subsequently accelerated by high potentials. Through selection of available parameters, it is possible to control the average energy of depositing species over the range from thermal ejection to above 100 eV per atom. It is within this range that optimum conditions for film growth are generally achieved. In the ICB deposition, characteristics of the deposition are mainly caused by both the structural characteristic of the clusters and the effects of ionization and acceleration of the clusters.

102 citations


Journal ArticleDOI
TL;DR: In this paper, the authors describe the deposition of superconducting and dielectric thin films by the laser evaporation technique, and the characterization of this process and possible optimization with regards to wavelength and pulse duration of the laser are discussed.
Abstract: We describe here the deposition of superconducting and dielectric thin films by the laser evaporation technique. The characterization of this process, and possible optimization with regards to wavelength and pulse duration of the laser will be discussed.

83 citations


Journal ArticleDOI
TL;DR: In this paper, a gas phase model of the photochemical deposition process was used to measure the deposition rate of a single-photon dissociation of the hexacarbonyl in the gas phase, yielding products that subsequently condense on the substrate surface.
Abstract: A quartz crystal microbalance has been used to measure the rates of photochemical deposition from Cr(CO)6, Mo(CO)6, and W(CO)6 induced by a focused frequency‐doubled argon ion laser (257 nm). The kinetic data indicate that deposition occurs via single‐photon dissociation of the hexacarbonyl in the gas phase, yielding products that subsequently condense on the substrate surface. This interpretation is supported by the observation of material deposited well outside the area of the substrate that is directly illuminated by the laser beam. A calculation of the deposit thickness versus radial distance from the center of the laser beam, using a simple gas‐phase model of the deposition process, provides an adequate fit to the observed thickness profile of a typical deposit. The presence of ripples in material deposited within the focal spot of the laser beam suggests that secondary photoinitiated dissociation of the gas‐phase photoproducts occurs after they condense on the substrate surface. Adsorption measureme...

83 citations


Patent
19 Aug 1988
TL;DR: In this paper, the authors present an apparatus and method for laser direct writing of materials onto a receiving substrate using a high power pulsed laser, which is accomplished by impinging the thin film of material with a pulsed LIDAR light from the laser light source causing material to be selectively "blown off" the optically transparent source support substrate and deposited onto the surface of the receiving substrate.
Abstract: The present invention provides an apparatus and method for laser direct writing of materials onto a receiving substrate using a high power pulsed laser. The invention includes a pulsed laser light source, a receiving substrate, disposed opposite the pulsed laser light source, and an optically transparent source support substrate positioned between the receiving substrate and the pulsed laser light source, wherein a surface of the optically transparent source support substrate facing the receiving substrate has coated thereon a thin film of material to be deposited on the receiving substrate. Laser direct writing using the invention is accomplished by impinging the thin film of material with a pulsed laser light from the pulsed laser light source causing material to be selectively "blown off" the optically transparent source support substrate and deposited onto the surface of the receiving substrate.

80 citations


Journal ArticleDOI
TL;DR: In this article, the authors used pulsed excimer laser evaporation technique to produce superconducting films with zero resistance at 80 K and a resistivity drop near 110 K. Transmission electron microscopy shows that the films are epitaxial with the substrate, with an abrupt and planar interface boundary.
Abstract: Oriented c‐axis thin films of Bi‐Ca‐Sr‐Cu‐O on [100] SrTiO3 substrates have been fabricated using the pulsed excimer laser evaporation technique. Deposition at room temperature in 1 mTorr oxygen followed by an 875 °C anneal in oxygen yields superconducting films with zero resistance at 80 K and a resistivity drop near 110 K, hinting at the presence of another superconducting phase. Transmission electron microscopy shows that the films are epitaxial with the substrate, with an abrupt and planar interface boundary. The observed crystal structure is consistent with diffraction results on bulk materials.

Patent
25 Jan 1988
TL;DR: In this article, an improved technique for providing deposition materials to the growth surface is described, where the gas carrying deposition materials is constrained to have axial symmetry, thereby providing a uniform deposition of materials on the substrate.
Abstract: In a chemical vapor deposition chamber, an improved technique for providing deposition materials to the growth surface is described. The gas carrying deposition materials is constrained to have axial symmetry thereby providing a uniform deposition of materials on the substrate. The gas can be initially directed toward the substrate with a generally uniform perpendicular velocity. The gas can be introduced into the deposition chamber through a multiplicity of apertures and is extracted from the vicinity of the substrate in a manner to preserve the axial symmetry. The apparatus permits convenient control of the deposition process by varying the distance between apparatus introducing the gas carrying the deposition materials and the substrate. The flow of gas minimizes the problems arising from autodoping of the growth layer of material. The flow of gas and generally small size of the deposition chamber minimize particulate contamination of the growing film.

Journal ArticleDOI
TL;DR: In this paper, the variation in the film properties as a function of the substrate temperature and oxygen partial pressure during deposition was studied, and conversion electron Mossbauser spectroscopic analysis showed that the stoichiometry and microstructure of such films depend on these deposition conditions.
Abstract: Iron oxide and ferrite films were prepared by pulsed ruby laser evaporation from the respective bulk materials on alumina substrates. The variation in the film properties as a function of the substrate temperature and oxygen partial pressure during deposition was studied. Conversion electron Mossbauser spectroscopic analysis showed that the stoichiometry and microstructure of such films depend on these deposition conditions, especially the oxygen partial pressure in the system. Typically it was observed that when laser deposition is performed by vaporizing α‐Fe2O3 in the oxygen partial pressure of 10−4 Torr, Fe3O4 thin films were formed while deposition at a background pressure of 10−6 Torr led to formation of FeO films. Similar experiments were also performed on zinc ferrite and it was observed that the nanosecond pulsed evaporation process transports the stoichiometry of metal constituents from the bulk to the film with a small degree of zinc enrichment. In addition to Mossbauer spectroscopy, other tech...


Journal ArticleDOI
TL;DR: A multichamber system specifically designed for growing Si-based dielectric films on processed and characterized semiconductor surfaces is described in this paper, where the electrical and structural properties of these films are discussed.
Abstract: A multichamber system specifically designed for growing Si‐based dielectric films on processed and characterized semiconductor surfaces is described. The system consists of a semiconductor surface preparation chamber, an in situ surface analysis chamber, a dielectric deposition chamber, and two load‐lock sample introduction chambers. Device quality silicon dioxide thin films have been grown on Si substrates. The electrical and structural properties of these films are discussed.

Patent
02 Nov 1988
TL;DR: Ion beam sputter-induced deposition using a single ion beam and a multicomponent target is capable of reproducibly producing thin films of arbitrary composition, including those which are close to stoichiometry as mentioned in this paper.
Abstract: Ion beam sputter-induced deposition using a single ion beam and a multicomponent target is capable of reproducibly producing thin films of arbitrary composition, including those which are close to stoichiometry. Using a quartz crystal deposition monitor and a computer controlled, well-focused ion beam, this sputter-deposition approach is capable of producing metal oxide superconductors and semiconductors of the superlattice type such as GaAs-AlGaAs as well as layered metal/oxide/semiconductor/superconductor structures. By programming the dwell time for each target according to the known sputtering yield and desired layer thickness for each material, it is possible to deposit composite films from a well-controlled sub-monolayer up to thicknesses determined only by the available deposition time. In one embodiment, an ion beam is sequentially directed via a set of X-Y electrostatic deflection plates onto three or more different element or compound targets which are constituents of the desired film. In another embodiment, the ion beam is directed through an aperture in the deposition plate and is displaced under computer control to provide a high degree of control over the deposited layer. In yet another embodiment, a single fixed ion beam is directed onto a plurality of sputter targets in a sequential manner where the targets are each moved in alignment with the beam under computer control in forming a multilayer thin film. This controlled sputter-deposition approach may also be used with laser and electron beams.

Journal ArticleDOI
TL;DR: In this article, a plasma deposition technique for amorphous aluminum oxide films is discussed, where a 450 kHz or 13.56 MHz power supply was used to generate the plasma and the deposition of the film was achieved at low plasma power using trimethyl-aluminum and carbon dioxide reactant sources.
Abstract: A plasma deposition technique for amorphous aluminum oxide films is discussed. A 450 kHz or 13.56 MHz power supply was used to generate the plasma and the deposition of the film was achieved at low plasma power using trimethyl-aluminum and carbon dioxide reactant sources. It has been found that for the low frequency plasma the growth is strongly dependent upon TMA concentration, indicating that the growth process is mass transport limited. On the other hand using the 13.56 MHz discharge results in a surface controlled growth rate. An increase in the deposition temperature up to 300° C makes the films more dense and lowers their etching rate. FTIR and ESCA measurements showed that oxidation is only completed with high CO2 concentrations and a deposition temperature above 250° C. The dielectric films were found to have a dielectric constant in the range 7.3=2-9 and a refractive index between 1.5–1.8 depending upon deposition conditions.

Journal ArticleDOI
TL;DR: Ionized cluster beam (ICB) is an ion-assisted film deposition technique by which high quality films of metals, dielectric and semiconductor can be formed at a low substrate temperature.
Abstract: Ionized cluster beam (ICB) deposition is an ion-assisted film deposition technique by which high quality films of metals, dielectric and semiconductor can be formed at a low substrate temperature. In the ICB process, film materials are vaporized from a confinement crucible under conditions which result in the formation of aggregates of atoms (clusters). Clusters are ionized by electron impact and subsequently accelerated by high potentials. Through selection of available parameters, it is possible to control the average energy of depositing species over the range from thermal to above 200 eV per atom, which make possible well controlled crystalline film deposition and epitaxy. In the ICB deposition, characteristics of the deposition are mainly caused by both the structural characteristic of the clusters and the effect of ionization and acceleration of the clusters. Unique features of ICB deposition, reactive-ICB deposition and simultaneous deposition by use of ICB and microwave ion source are described with respect to the kinetic energy and the ionic charge by comparing those of deposition methods in plasma.

Journal ArticleDOI
TL;DR: In this article, the dependence of a-Si∶H film deposition by laser-induced decomposition of SiH4 on the different process variables is studied, and the gas phase temperature in the beam center, produced by CO2 laser irradiation in parallel configuration, is estimated using a simple energy balance model.
Abstract: The dependence of a-Si∶H film deposition by laser-induced decomposition of SiH4 on the different process variables is studied. The gas phase temperature in the beam center, produced by CO2 laser irradiation in parallel configuration, is estimated using a simple energy balance model. The surface temperature is measured with high accuracy employing a Ni sensor (250°–400 °C). The deposition rate and film properties such as the hydrogen content and the optical energy gap are determined as a function of these parameters. The production of H2 (≈10%), Si2H6 (≈2%), and Si3H8 in the gas phase during laser irradiation is proved by a mass spectrometric analysis. The chemical reaction processes induced in the gas phase and at the surface are discussed. A mechanism explaining the main features of the complicated chemistry involved is developed.

Journal ArticleDOI
TL;DR: In this article, magnetic field measurements on micron-sized wires of the thin-film high Tc superconductor Y1 Ba2 Cu3 O7−x made by pulsed laser deposition reveal an exponential suppression of the critical current with magnetic field.
Abstract: Magnetotransport measurements on micron‐sized wires of the thin‐film high Tc superconductor Y1 Ba2 Cu3 O7−x made by pulsed laser deposition reveal an exponential suppression of the critical current with magnetic field, and a power law dependence of the critical current on reduced temperature. We ascribe this behavior to crystallographic defects in the film which behave as superconductor/normal‐metal/superconductor weak links in a magnetic field. From the measurements we estimate a critical current density of 106 A cm−2 in a field of 16 T at 4.2 K.

Journal ArticleDOI
TL;DR: A study of the major deposition parameters including source material, oxygen partial pressure, substrate temperature, and deposition rate affecting the optical quality of electron beam evaporated TiO(2) films is presented.
Abstract: A study of the major deposition parameters including source material, oxygen partial pressure, substrate temperature, and deposition rate affecting the optical quality of electron beam evaporated TiO(2) films is presented. After careful optimization of these parameters it is possible to reproducibly deposit TiO(2) films from TiO(2) source material mixed with 5% CeO(2) at an oxygen partial pressure of 5 x 10(-5) Torr, a substrate temperature of 320 degrees C, and a deposition rate of 2 A/s.

Journal ArticleDOI
TL;DR: Sputtering provides a very useful method for preparing a wide range of materials in thin film form as discussed by the authors and has been applied in many applications from microelectronics to decorative coating of automobiles.
Abstract: Sputtering provides a very useful method for preparing a wide range of materials in thin film form. Since the advent of magnetron systems, providing higher deposition rates and very flexible configurations, sputter deposition has been applied in many applications from microelectronics to decorative coating of automobiles. The high energy of sputtered atoms and the plasma environment make it possible to deposit a wide variety of films, some not obtainable otherwise, with good control over the film properties. Sputtering is not a simple technique, but it is a powerful one when used appropriately.

Journal ArticleDOI
TL;DR: In CVD, a solid material is deposited from gaseous precursors onto a substrate. The substrate is typically heated to promote the deposition reaction and/or provide sufficient mobility of the adatoms to form the desired structure.
Abstract: Chemical vapor deposition (CVD) is one of the few deposition processes in which the deposited phase is produced in situ via chemical reaction(s). Thus the vapor source for CVD can consist of high vapor pressure species at moderate temperatures and yet deposit very high-melting phases. For example, pure TiB2, which melts at 3225°C, can be produced at 900°C from TiCl4, BC13, and H2.Chemical vapor deposition and its variants such as low pressure CVD (LPCVD), plasma-assisted CVD (PACVD), and laser CVD (LCVD) have been active areas of research for many years. Recent review articles have contained extensive lists of the phases deposited by CVD, which include most of the metals and many carbides, nitrides, borides, silicides, and sulfides. The techniques have found increased acceptance as commercial methods for the fabrication of films and coatings which are fundamental to the semiconductor device and the high-performance tool bit industries. They have been used to prepare multiphase-multilayer coatings, stand-alone bodies, and fiber-reinforced composites. As the demand increases for more complex and sophisticated materials, it is expected that CVD will play a still larger role.In CVD a solid material is deposited from gaseous precursors onto a substrate. The substrate is typically heated to promote the deposition reaction and/or provide sufficient mobility of the adatoms to form the desired structure. Chemical vapor deposition was performed for the first time when early humans inadvertently coated cooking utensils with soot from the campfire. In this CVD process, hydrocarbons generated by the heated wood pyrolyzed on the utensil surface, depositing carbon.

Journal ArticleDOI
TL;DR: In this article, it was shown that the stoichiometry of the deposited film can be varied between FeO and Fe3O4 by controlling the oxygen partial pressure during deposition over a range from 5×10−7 to 10−4 Torr.
Abstract: Iron oxide films have been deposited on alumina substrates by pulsed ruby laser evaporation from a bulk α‐Fe2O3 pellet. The films have been characterized by using the techniques of conversion electron Mossbauer spectroscopy, Rutherford backscattering, and scanning electron microscopy. It is demonstrated that the stoichiometry of the deposited film can be varied between FeO and Fe3O4 by controlling the oxygen partial pressure during deposition over a range from 5×10−7 to 10−4 Torr. It is further shown that the Fe3O4 film can be converted into γ‐Fe2O3 by suitable thermal annealing treatment.

Journal ArticleDOI
TL;DR: In this paper, the rate of photolytic laser chem. vapor deposition (LCVD) of Pt was measured for l = 350 nm as a function of light intensity and metal pressure.
Abstract: The rate of cw photolytic laser chem. vapor deposition (LCVD) of Pt was measured for l = 350 nm as a function of light intensity and metalorg. vapor pressure. The growth of the metal films was studied in situ and in real time by monitoring optical transmission. At low intensities the transmitted light decreases monotonically with time, and the LCVD process is photolytic with its rate limiting step in the surface adlayer. At higher intensities 2 distinct time domains were obsd. An improved method for distinguishing between adlayer and gas-phase limiting processes is demonstrated. These observations are confirmed by studying the photolytic deposition rates while varying the thickness of the adlayer.

Journal ArticleDOI
TL;DR: In this article, laser assisted chemical vapor deposition (LCVD) is used for low temperature selective epitaxy of III-V compounds with great potential for maskless multicomponent device integration on the same wafer.

Journal ArticleDOI
TL;DR: In this paper, thin films of Ho1Ba2Cu3O7 − x and Y1Ba 2Cu3 O7 −x were deposited on SrTiO3 and Al2O3, substrates by pulsed laser deposition of high-Tc bulk superconductor pellets in vacuum.
Abstract: Thin films of Ho1Ba2Cu3O7 − x and Y1Ba2Cu3O7 − x were deposited on SrTiO3 and Al2O3, substrates by pulsed laser deposition of high-Tc bulk superconductor pellets in vacuum. Following annealing in O2 at 800–900 °C the films were superconducting with typical Tc (50%) = 89 K and transition widths of 10 K. Rutherford backscattering spectrometry (RBS) and secondary ion mass spectrometry (SIMS) were utilized to study the stoichiometry of the as-deposited films for laser energy, densities between 0.11 and 4.5 J cm−2. The films were deficient in holmium and yttrium for energy densities below 0.6 and 0.4 J cm −2, respectively. The films were stoichiometric for fluences above 0.6 J cm−2. In addition, preliminary time dependence and spectroscopic observations of the laser-produced plasma are presented. The results indicate an ablation mechanism that at high energy densities preserves stoichiometry. TEM and x-ray characterization of annealed, superconducting Ho1Ba2Cu3O7 − x films on (100) SrTiO3 showed mixed regions of epitaxially oriented 1:2:3 material with either the c axis or a axis oriented along the surface normal. The a-axis-oriented material grew preferentially in the films with b, c, twinning.

Journal ArticleDOI
TL;DR: In this paper, the authors discuss the properties of these films in device structures utilizing crystalline Si, Ge and (In, Ga)As and then present the results of their initial studies of dielectric film deposition onto CdTe surfaces.

Journal ArticleDOI
01 Jan 1988-Vacuum
TL;DR: In this paper, the pulsed plasma process and equipment are described in detail, and applications of its unique capabilities are discussed, where high power rf is pulsed for both deposition and etching.

Journal ArticleDOI
TL;DR: In this paper, a new type of chemical vapor deposition method, named "Catalytic-CVD" method, is presented, in which deposition gases are decomposed by catalytic or pyrolytic reaction between deposition gases and a heated catalyzer, and films are thermally grown on a substrate at temperatures lower than 300°C without any help from glow discharge plasma.
Abstract: A new type of chemical vapor deposition method, named ‘‘Catalytic‐CVD’’ method, is presented. In the method, deposition gases are decomposed by catalytic or pyrolytic reaction between deposition gases and a heated catalyzer, and films are thermally grown on a substrate at temperatures lower than 300 °C without any help from glow discharge plasma. Hydro‐fluorinated amorphous silicon (a‐Si:F:H) films are deposited by this method using both a SiF2 and H2 gas mixture and a SiH2F2 and H2 mixture. It is found that a very high quality a‐Si:F:H film can be obtained, and for instance, that the photosensitivity for AM‐1 of 100 mW/cm2 exceeds 106 and the spin density is as low as 6×1015 cm−3.