Very high frequency hydrogen plasma treatment of growing surfaces: a study of the p-type amorphous to microcrystalline silicon transition

Summonte, C.; Rizzoli, R.; Desalvo, A.; Zignani, F.; Centurioni, E.; Pinghini, R.; Gemmi, Mauro

doi:10.1016/s0022-3093(99)00755-3

Cited by 18 publications

(6 citation statements)

References 13 publications

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“…We stress the fact that such a value is not, or just partly, due to a larger hydrogen concentration, as indicated by the dependence of E 04 on x regardless of H% [see Fig. In a previous paper 63 we reported, for half the power density used in this paper, an etching rate for a-Si: H of 0.05 nm/ s for 50 SCCM H 2 , and up to 0.2 nm/ s for 100 SCCM H 2 , which is a flow rate similar to that used for the 90-series. Rather, the absence of carbon in sp 2 configuration also contributes to high values for E 04 .…”

Section: Discussionmentioning

confidence: 91%

“…The observation is corroborated by the 0.2-0.4 eV larger E 04 obtained for the same x and lower hydrogen concentration, compared with rf deposited samples. 63 The larger SiC bond concentration, the almost total disappearing of methylated silicon groups in the latter case, and the overall structural differences described above can therefore be ascribed to the change in the plasma chemistry between the 48-and 90-sample series. In a previous paper 63 we reported, for half the power density used in this paper, an etching rate for a-Si: H of 0.05 nm/ s for 50 SCCM H 2 , and up to 0.2 nm/ s for 100 SCCM H 2 , which is a flow rate similar to that used for the 90-series.…”

Section: Discussionmentioning

confidence: 99%

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Wide band-gap silicon-carbon alloys deposited by very high frequency plasma enhanced chemical vapor deposition

Summonte

Rizzoli

Bianconi

et al. 2004

Journal of Applied Physics

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High rate deposition of diamond like carbon films by very high frequency plasma enhanced chemical vapor deposition at 100 MHz Wide band gap amorphous hydrogenated carbon films grown by plasma enhanced chemical vapor depositionThe use of very high frequency (VHF) plasma enhanced chemical vapor deposition in a capacitive discharge is investigated to fabricate hydrogenated amorphous silicon carbon alloys, using silane and methane as silicon and carbon precursors, respectively, and hydrogen dilution of the gas mixture. The properties of samples differ significantly from that is normally observed for rf deposition. A wide band-gap material is obtained, with a carbon ratio ranging from 0.2 to 0.63. An energy gap up to 3.4 eV is measured, indicating a large sp 3 content. The most interesting properties are observed using 90% hydrogen dilution and 350°C as substrate temperature. In this case, a Siu C bond concentration up to 6 ϫ 10 22 cm −3 was measured for stoichiometric samples, associated to a highly crosslinked structure and no detectable Siu CH 3 bending signal. The role of hydrogen in determining the optical properties of the film is established and is shown to affect mainly the valence electron concentration. Based on the free energy model, hydrogen bonding is observed to lie in between a random and chemically ordered configuration. The results are obtained at a deposition rate much larger than both rf and electron cyclotron resonance deposition, and are associated to a limited gas consumption, both aspects being advantageous for practical applications. The large Siu C bond concentration, associated to a limited silicon and carbon hydrogenation, makes the VHF deposited a-SiC : H a good starting material for subsequent crystallization.

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Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Wide band-gap silicon-carbon alloys deposited by very high frequency plasma enhanced chemical vapor deposition

Summonte

Rizzoli

Bianconi

et al. 2004

Journal of Applied Physics

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“…Etching and posttreatment of silicon with hydrogen glow discharge plasma [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] or with atomic hydrogen produced by hot filament 4,17,18 have again received significant attention recently in the context of new, alternative gases and processes for patterning in microelectronic device fabrication, [1][2][3] posttreatment of thin-film silicon in order to enhance its crystallization, [11][12][13][14] cleaning and passivation of wafers prior to the deposition of epitaxial films, [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] and cleaning of devices for controlled nuclear research 38,39 and of equipment for plasma-induced deposition of thin films.…”

Section: Introductionmentioning

confidence: 99%

Role of oxygen impurities in etching of silicon by atomic hydrogen

Vepřek

Wang

Vepřek-Heijman

2008

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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In a pure-hydrogen glow discharge plasma, the etch rate of silicon increases with increasing temperature up to about Ն1100 Å / s at 60-80°C and, upon a further increase of the temperature, etch rate strongly decreases, showing Arrhenius-like dependence with negative apparent activation energy of −1.5 kcal/ mol. When the Si sample is at the floating potential, oxygen impurities of Ն10 at. ppm strongly decrease the etch rate. At more than 70 ppm of oxygen, the etching stops. Oxygen adsorbed on the Si surface can be removed by ion bombardment when negative potential is applied to the Si sample and the Si is then etched chemically by H atoms. The etching by atomic hydrogen is isotropic in an oxygen-free system. A controllable addition of a few ppm of oxygen in combination with negative bias of the Si sample results in highly anisotropic etching with thin oxide acting as side-wall passivation.

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“…The Brüggeman effective medium approximation (BEMA) and a multilayer model ( Optical software [22]) were used to fit the R and T spectra measured ex situ in the UV-NIR range [23,24]. BEMA approximation is available in the multilayer model in order to implement intermixing of adjacent layers into the optical model [25].…”

Section: Methodsmentioning

confidence: 99%

“…UV-NIR spectrophotometric measurements were performed with an optic fiber AVANTES, model AvaSpec2048-USB2 (Eerbeek, Holland), able to obtain reflectance and transmittance (R and T) spectra in a wavelength range between 200 nm and 1100 nm. The Brüggeman effective medium approximation (BEMA) and a multilayer model ( Optical software [ 22 ]) were used to fit the R and T spectra measured ex situ in the UV-NIR range [ 23 , 24 ]. BEMA approximation is available in the multilayer model in order to implement intermixing of adjacent layers into the optical model [ 25 ].…”

Section: Methodsmentioning

confidence: 99%

Characterization of Doped Amorphous Silicon Thin Films through the Investigation of Dopant Elements by Glow Discharge Spectrometry: A Correlation of Conductivity and Bandgap Energy Measurements

Sánchez

Lorenzo

Menéndez³

et al. 2011

IJMS

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The determination of optical parameters, such as absorption and extinction coefficients, refractive index and the bandgap energy, is crucial to understand the behavior and final efficiency of thin film solar cells based on hydrogenated amorphous silicon (a-Si:H). The influence of small variations of the gas flow rates used for the preparation of the p-a-SiC:H layer on the bandgap energy, as well as on the dopant elements concentration, thickness and conductivity of the p-layer, is investigated in this work using several complementary techniques. UV-NIR spectrophotometry and ellipsometry were used for the determination of bandgap energies of four p-a-SiC:H thin films, prepared by using different B2H6 and SiH4 fluxes (B2H6 from 12 sccm to 20 sccm and SiH4 from 6 sccm to 10 sccm). Moreover, radiofrequency glow discharge optical emission spectrometry technique was used for depth profiling characterization of p-a-SiC:H thin films and valuable information about dopant elements concentration and distribution throughout the coating was found. Finally, a direct relationship between the conductivity of p-a-SiC:H thin films and the dopant elements concentration, particularly boron and carbon, was observed for the four selected samples.

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Very high frequency hydrogen plasma treatment of growing surfaces: a study of the p-type amorphous to microcrystalline silicon transition

Cited by 18 publications

References 13 publications

Wide band-gap silicon-carbon alloys deposited by very high frequency plasma enhanced chemical vapor deposition

Wide band-gap silicon-carbon alloys deposited by very high frequency plasma enhanced chemical vapor deposition

Role of oxygen impurities in etching of silicon by atomic hydrogen

Characterization of Doped Amorphous Silicon Thin Films through the Investigation of Dopant Elements by Glow Discharge Spectrometry: A Correlation of Conductivity and Bandgap Energy Measurements

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