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Journal ArticleDOI

Low filament temperature deposition of a‐Si:H by hot‐wire chemical vapor deposition

15 Sep 1995-Journal of Applied Physics (American Institute of Physics)-Vol. 78, Iss: 6, pp 3776-3783
TL;DR: In this article, a kinetic growth model for hot-wire chemical vapor deposition in the Tfil∼1200°C regime is proposed, and the Optoelectronic properties are controlled by the substrate temperature Tsub, and show different dependences for new and old filaments.
Abstract: Hydrogenated amorphous silicon, a‐Si:H, is deposited from silane and hydrogen by hot‐wire chemical vapor deposition using a tungsten wire filament at a temperature Tfil=1200 °C. Film properties depend on whether the films were deposited using filaments with an accumulated deposition time lower than 90 min (‘‘new’’ filaments) or longer than 90 min (‘‘old’’ filaments). The deposition rate for films deposited with ‘‘new’’ filaments is 4 times higher than that for aged filaments. For ‘‘new’’ filaments, a monotonic increase of the growth rate, rd, with the pressure is observed, as well as a maximum of rd for FH2/FSiH4 close to unity. The optoelectronic properties are controlled by the substrate temperature Tsub, and show different dependences for ‘‘new’’ and ‘‘old’’ filaments. The Urbach band tail energy, Eu, is lower for films deposited with ‘‘new’’ filaments. A kinetic growth model for hot‐wire chemical vapor deposition in the Tfil∼1200 °C regime is proposed.
Citations
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Journal ArticleDOI
TL;DR: In this article, the authors consider three types of systems: Carbon Black-Polymer composites, metal-insulator cermets and hydrogenated microcrystalline silicon.
Abstract: Classical percolation theory is concerned with the onset of geometrical connectivity and the accompanied onset of electrical connectivity in disordered systems. It was found, however, that in many systems, such as various composites, the geometrical and electrical onsets of the connectivity are not simultaneous and the correlation between them depends on physical processes such as tunneling. The difference between the above two types of systems and the consequences for the electrical transport properties of the latter composites have been largely ignored in the past. The application of scanning local probe microscopies and some recent theoretical developments have enabled a better understanding of the latter systems and their sometimes "strange" behavior as bona fide percolation systems. In this review we consider the above issues and their manifestation in three types of systems: Carbon Black–Polymer composites, metal–insulator cermets and hydrogenated microcrystalline silicon.

203 citations

Journal ArticleDOI
TL;DR: The optical, electronic and structural properties of thin films deposited by Hot-Wire chemical vapor deposition with filament temperatures, Tfil, between 1500 and 1900 C from silane and hydrogen are studied in this paper.
Abstract: The optical, electronic and structural properties of thin films deposited by Hot‐wire chemical vapor deposition with filament temperatures, Tfil, between 1500 and 1900 °C from silane and hydrogen are studied. The substrate temperature, Tsub, was kept constant at 220 °C. Amorphous silicon films (a‐Si:H) are obtained at high filament temperatures, low deposition pressures and low hydrogen‐to‐silane flow rate ratio (Tfil∼1900 °C, p<30 mTorr and FH2/FSiH4≤1). At these deposition conditions, high growth rates are observed (rd≥10 As−1) both with and without hydrogen dilution, and no silicon deposition was observed on the filaments. However, if a lower filament temperature is used (Tfil∼1500 °C) a transition from a‐Si:H to microcrystalline silicon (μc‐Si:H) occurs as the pressure is decreased from above 0.3 Torr to below 0.1 Torr. The highest dark conductivity and lowest activation energy, of ∼1 Scm−1 and <0.1 eV, respectively, were observed for μc‐Si:H deposited at p∼50 mTorr. In this Tfil regime, μc‐Si:H growt...

50 citations

Journal ArticleDOI
TL;DR: In this paper, the electronic and structural properties of amorphous (a-Si:H) and micro-crystalline (μc-Si-H) silicon thin films deposited at substrate temperatures of 25 and 100°C by hot-wire chemical vapor deposition is studied.
Abstract: The gas phase doping of amorphous (a-Si:H) and microcrystalline (μc-Si:H) silicon thin films deposited at substrate temperatures of 25 °C and 100 °C by hot-wire chemical vapor deposition is studied. Phosphine was used for n-type doping and diborane for p-type doping. The electronic and structural properties of the doped films are studied as functions of hydrogen dilution. Films were deposited on glass and polyethylene terephthalate. Similar dark conductivities, σd, were obtained for the doped films deposited on either substrate. σd above 10−6 Ω−1 cm−1 were obtained for a-Si:H films doped n-type at 25 °C and 100 °C (σd>10−4 Ω−1 cm−1) and for a-Si:H doped p-type only at 100 °C. σd, equal or above 10−1 Ω−1 cm−1, were obtained for μc-Si:H doped p-type at 25 °C and 100 °C for μc-Si:H doped n-type only at 100 °C. Isochronal annealing at temperatures up to 200 °C reveals that, while the dopants are fully activated in microcrystalline samples, they are only partially activated in amorphous films deposited at a low substrate temperature.

39 citations

Journal ArticleDOI
TL;DR: In this paper, a modification of argon plasma-pretreated single-crystal silicon wafer surface via UV-induced graft polymerization with various functional monomers, such as acrylamide (AAm), N,N-diamethylaminoethyl methacrylate (DMAEMA), and 2,2,2-trifluoroethyl acrylate(TFEA), was achieved.
Abstract: Modification of argon plasma-pretreated single-crystal silicon wafer surface via UV-induced graft polymerization with various functional monomers, such as acrylamide (AAm), N,N‘-diamethylaminoethyl methacrylate (DMAEMA), and 2,2,2-trifluoroethyl acrylate (TFEA), was achieved. The modified Si(100) surfaces were characterized by X-ray photoelectron spectroscopy (XPS), imaging XPS, atomic force microscopy (AFM), and water contact angle measurements. The graft polymerization was affected by plasma pretreatment time and UV irradiation time. XPS results suggest that mild and brief plasma treatment is sufficient to cause surface oxidation and to generate sufficient peroxides and hydroxyl peroxides for the subsequent UV-induced graft polymerization in the presence of a vinyl monomer. Prolonged plasma treatment and the accompanying overoxidation of the silicon surface have an adverse effect on the graft polymerization. For all the cases investigated, the XPS results revealed that the grafted polymers form a thin l...

34 citations

References
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MonographDOI
R. A. Street1
30 Aug 1991
TL;DR: In this article, the electronic density of states of amorphous silicon and their electronic states have been investigated in terms of defect reactions, thermal equilibrium and metastability, as well as their electronic properties.
Abstract: 1. Introduction 2. Growth and structure of amorphous silicon 3. The electronic density of states 4. Defects and their electronic states 5. Substitutional doping 6. Defect reactions, thermal equilibrium and metastability 7. Electronic transport 8. Recombination of excess carriers 9. Contacts, interfaces and multilayers 10. Amorphous silicon device technology.

2,003 citations

Book
01 Jan 1985
TL;DR: In this paper, heat transfer: a basic approach, heat transfer, a basic heat transfer approach, Heat transfer, basic approach for heat transfer in a basic way, Heat Transfer: a Basic approach for Heat transfer.
Abstract: Heat transfer: a basic approach , Heat transfer: a basic approach , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

842 citations

Journal ArticleDOI
TL;DR: In this paper, Gudden et al. verstrichen the Elektronenverluste auf dem Wege zur Anode in reinen AgCl-Kristallen.
Abstract: Seit der Auffindung des lichtelektrischen Primarstromes in isolierenden Kristallen sind rund 10 Jahre verstrichen. Seither sind in der Kenntnis des Kristallmaterials und in der Versuchstechnik erhebliche Fortschritte erzielt worden. Daher sollen jetzt die alten Beobachtungen von Gudden und Pohl mit neuzeitlichen Mitteln wiederholt und erweitert werden. So behandelt die vorliegende Arbeit zum ersten Male quantitativ die Elektronenverluste auf dem Wege zur Anode. Die Ergebnisse sind aui S. 236 und 237 zusammengestellt. Die Arbeit enthalt auserdem in § 8 Angaben uber die Quantenausbeute der lichtelektrischen Elektronen-abspaltung in reinen AgCl-Kristallen und solchen mit 0,05Mol-% CuCl-Zusatz.

680 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that hydrogenated amorphous silicon containing as little as 1/10 the bonded H observed in device-quality glow discharge films have been deposited by thermal decomposition of silane on a heated filament.
Abstract: Device‐quality hydrogenated amorphous silicon containing as little as 1/10 the bonded H observed in device‐quality glow discharge films have been deposited by thermal decomposition of silane on a heated filament. These low H content films show an Urbach edge width of 50 mV and a spin density of ∼1/100 as large as that of glow discharge films containing comparable amounts of H. High substrate temperatures, deposition in a high flux of atomic H, and lack of energetic particle bombardment are suggested as reasons for this behavior.

464 citations