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Ian S. Osborne

Bio: Ian S. Osborne is an academic researcher. The author has contributed to research in topics: Amorphous silicon & Silane. The author has an hindex of 5, co-authored 8 publications receiving 57 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, hydrogenated amorphous silicon films have been deposited from mixtures of dichlorosilane (SiH2Cl2) and silane by plasma enhanced chemical vapour deposition.
Abstract: Hydrogenated amorphous silicon films have been deposited from mixtures of dichlorosilane ( SiH2Cl2) and silane by plasma enhanced chemical vapour deposition. The deposition rate is found to increase with the addition of SiH2Cl2. At a given rf power, the deposition rate decreases with increasing total flow rate, opposite to that found for deposition with only silane. These results are compared to optical emission data measured under identical deposition conditions, and are discussed in terms of electron attachment to the chlorinated species which modifies the electron energy distribution within the plasma.

13 citations

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TL;DR: In this paper, a linear relationship between the deposition rate and optical emission spectroscopy signal intensity was observed suggesting that the high deposition rate is due to enhancement of gas-phase processes.
Abstract: We report enhancement of the deposition rate of hydrogenated amorphous silicon without powder formation and without deterioration of its optoelectronic properties by plasma chemical vapor deposition from silane and dichlorosilane gas mixtures. A linear relationship between the deposition rate and optical emission spectroscopy signal intensity was observed suggesting that the high deposition rate is due to enhancement of gas-phase processes. The rate of film growth increased with power density as well as with the ratio of dichlorosilane to silane mixture, but decreased with total flow rate. These results were interpreted as resulting for the negative ions being confined in the discharge volume by the plasma potential, resulting in a higher electron temperature. The increased electron temperature leads to a higher decomposition rate of silane in the gas phase.

12 citations

Journal ArticleDOI
TL;DR: In this article, hydrogenated amorphous silicon films have been grown by radio frequency (rf) plasma chemical vapor deposition with the addition of small amounts (up to 20%) of dichlorosilane to the silane.
Abstract: Hydrogenated amorphous silicon films have been grown by radio frequency (rf) plasma chemical vapor deposition with the addition of small amounts (up to 20%) of dichlorosilane to the silane. Results show that as the amount of dichlorosilane is increased, the films are more resilient to the creation of light induced defects. Under intense pulsed laser illumination (5 mJ/pulse, 10 ns, 10 Hz) the steady state defect density measured by the constant photocurrent method (CPM) is reduced by over one order of magnitude to 4×1016 cm−3 as compared to ∼5×1017 cm−3 for films grown under identical conditions with pure silane. Furthermore, there is a threefold increase in the deposition rate over the range of mixture ratios studied here.

9 citations

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TL;DR: In this article, a triode electrode configuration with a wire mesh placed between the cathode and anode of a conventional diode type PECVD system was used to control the optoelectronic properties of hydrogenated amorphous silicon (a-Si:H).
Abstract: A new deposition parameter in the plasma enhanced chemical vapour deposition (PECVD) technique for the control of the optoelectronic properties of hydrogenated amorphous silicon (a-Si:H) is presented. The technique utilises a triode electrode configuration with a wire mesh placed between the cathode and anode of a conventional diode type PECVD system. A dc bias, applied to the mesh, affects the plasma-substrate distance or the extent of plasma confinement between the mesh and the cathode, and subtly alters the gas phase chemistry in the plasma. Using this technique, films of undoped a-Si:H have been deposited with pure silane as the source gas. Our results show that the defect density, hydrogen content, and hydrogen bonding configuration are determined by the mesh bias. Measurement of the defect density of the as-grown films by the constant photocurrent method (CPM) reveals that this technique can be used to produce high quaility films with low defect density (<5× 1014 cm-3) by application of an appropriate bias on the mesh during deposition.

9 citations

Journal ArticleDOI
TL;DR: In this article, the distributions of annealing energies of light-induced defects obtained from a study of the defect-annealing kinetics of films grown from silane and dichlorosilane gas mixtures by plasma enhanced chemical vapour deposition are reported.
Abstract: The distributions of annealing energies of light-induced defects obtained from a study of the defect annealing kinetics of films grown from silane and dichlorosilane gas mixtures by plasma enhanced chemical vapour deposition are reported. The results are modelled using a gaussian distribution of annealing energies. The addition of dichlorosilane is found to affect the magnitude and position of the defect annealing energy distribution. As measured by the constant photocurrent method, these films show an increased stability to the creation of light-induced defects under intense pulsed laser illumination.

5 citations


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Journal ArticleDOI
TL;DR: In this article, the piezoelectric properties of relaxor based ferroelectric single crystals, such as Pb(Zn1/3Nb2/3)O3 and PbTiO3, were investigated for electromechanical actuators.
Abstract: The piezoelectric properties of relaxor based ferroelectric single crystals, such as Pb(Zn1/3Nb2/3)O3–PbTiO3 and Pb(Mg1/3Nb2/3)O3–PbTiO3 were investigated for electromechanical actuators. In contrast to polycrystalline materials such as Pb(Zr,Ti)O3, morphotropic phase boundary compositions were not essential for high piezoelectric strain. Piezoelectric coefficients (d33’s)>2500 pC/N and subsequent strain levels up to >0.6% with minimal hysteresis were observed. Crystallographically, high strains are achieved for 〈001〉 oriented rhombohedral crystals, although 〈111〉 is the polar direction. Ultrahigh strain levels up to 1.7%, an order of magnitude larger than those available from conventional piezoelectric and electrostrictive ceramics, could be achieved being related to an E-field induced phase transformation. High electromechanical coupling (k33)>90% and low dielectric loss <1%, along with large strain make these crystals promising candidates for high performance solid state actuators.

3,766 citations

Journal ArticleDOI
TL;DR: In this paper, material development of the piezoelectric ceramic and new opportunities for higher temperature materials are discussed, and an important consideration in developing low fire ceramics is the flux selection for a given system, and these must be selected to limit electrode-ceramic interface reactions in both Ag/Pd and copper-metallized electrode actuators.
Abstract: Piezoelectric actuators are at an important stage of their development into a large component market. This market pull is for dynamically driven actuators for Diesel injector valves in automobiles. Cost, yield, and reliability are important concerns for the automobile industry. A number of these concerns relate back to basic material science issues in the manufacture of the piezoelectric actuators. This paper discusses material development of the piezoelectric ceramic and new opportunities for higher temperature materials. An important consideration in developing low-fire ceramics is the flux selection for a given system, and these must be selected to limit electrode-ceramic interface reactions in both Ag/Pd and copper-metallized electrode actuators.

215 citations

Journal ArticleDOI
TL;DR: In this article, a two-stage i-layer growth process was designed such that the initial stage of the i layer (∼200 A) is deposited at much higher R than the bulk to ensure that the film remains within the amorphous side of the a→μc phase boundary, yet as close as possible to this boundary at low I-layer thicknesses.
Abstract: Hydrogenated amorphous silicon (a-Si:H) p–i–n solar cell performance has been optimized using a two-step i-layer growth process. This effort has been guided by real-time spectroscopic ellipsometry (RTSE) studies of the nucleation and growth of a-Si:H films by plasma-enhanced chemical vapor deposition at 200 °C using a variable H2-dilution gas flow ratio R=[H2]/[SiH4]. RTSE studies during film growth with R>15 reveal a transition from the amorphous to microcrystalline (a→μc) phase at a critical thickness that decreases with increasing R. From such results, the optimum two-step process was designed such that the initial stage of the i layer (∼200 A) is deposited at much higher R than the bulk to ensure that the film remains within the amorphous side of the a→μc phase boundary, yet as close as possible to this boundary at low i-layer thicknesses.

214 citations

Journal ArticleDOI
TL;DR: The history of piezoelectric perovskites is reviewed and forecasts future development trends, including Uchino’s discoveries such as the Pb(Mg1/3Nb2/3)O3–PbTiO3 electrostrictor, and five key trends in the development of Piezomaterials: performance to reliability, hard to soft, macro to nano, homo to hetero, and single to multi-functional.

91 citations

Journal ArticleDOI
TL;DR: In this paper, various experimental results concerning this problem and various models for the photocreation of dangling bonds which is thought to be the main origin of the degradation are introduced and discussed.
Abstract: Hydrogenated amorphous silicon and related alloy films have attracted much attention because of the wide application of these films in devices such as thin-film transistors and solar cells. However, the degradation of these films caused by intense illumination is a serious shortcoming. In this review, various experimental results concerning this problem and various models for the photocreation of dangling bonds which is thought to be the main origin of the degradation are introduced and discussed. Degradation in the device performance, some efforts to overcome the degradation and some metastable defects other than photocreated ones are also briefly introduced.

87 citations