Conduction- and valence-band offsets at the hydrogenated amorphous silicon-carbon/crystalline silicon interface via capacitance techniques

Heterostructure Schottky diode samples each composed of a sub-micron thick layer of intrinsic hydrogenated amorphous silicon-carbon (a-Si1−xCx:H) deposited on an n-type crystalline silicon (c-Si) substrate are used to measure the a-Si1−xCx:H/c-Si band offsets via junction capacitance techniques. The samples range in carbon concentration from x=0.0−0.3. First, a thermally activated capacitance step due to the response of defects at the amorphous/crystalline interface is evident in capacitance vs. temperature spectra taken on all these samples. The bias-dependence of this step’s activation energy provides a direct measure of the a-Si1−xCx:H/c-Si interface potential as a function of c-Si depletion width in each sample. By application of Poisson’s equation, we find that the a-Si1−xCx:H/c-Si conduction band offset ΔEc. increases from 0.00 to 0.10 eV as x increases from 0.00 to 0.26. Second, while under reverse-bias at low temperature, we optically pulsed each sample with c-Si band-gap light to create trapped holes at the a-Si1−xCx:H/c-Si valence band offset ΔEV. By noting the threshold for the subsequent optical release of these trapped holes by sub-band gap light, we found that ΔEV increases from 0.67 to ≥0.83 eV as x increases from 0.00 to 0.26.

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Valence band structure of hydrogenated amorphous silicon-carbon alloys

Journal of Non-Crystalline Solids ◽

10.1016/0022-3093(83)90645-2 ◽

1983 ◽

Vol 59-60 ◽

pp. 561-564 ◽

Cited By ~ 14

Author(s):

Yoshifumi Katayama ◽

Toshikazu Shimada ◽

Tsuyoshi Uda ◽

Keisuke L.I. Kobayashi ◽

Chang-gen Jiang ◽

...

Keyword(s):

Band Structure ◽

Amorphous Silicon ◽

Valence Band ◽

Hydrogenated Amorphous Silicon ◽

Valence Band Structure ◽

Silicon Carbon ◽

Hydrogenated Amorphous

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Photo-Oxidation of Hydrogenated Amorphous Silicon-Carbon Alloys

MRS Proceedings ◽

10.1557/proc-158-181 ◽

1989 ◽

Vol 158 ◽

Author(s):

P. John ◽

I.M. Odeh ◽

A. Qayyum ◽

J.I.B. Wilson

Keyword(s):

Amorphous Silicon ◽

Photoelectron Spectroscopy ◽

Crystalline Silicon ◽

Hydrogenated Amorphous Silicon ◽

Rf Discharge ◽

Silicon Substrates ◽

Capacitively Coupled ◽

X Ray ◽

Silicon Carbon ◽

Hydrogenated Amorphous

ABSTRACTHydrogenated amorphous silicon-carbon alloys, a-Si:C:H, have been deposited as thin films (d=0.1-0.5 micron) on crystalline silicon substrates from a capacitively coupled rf discharge in silane-propane mixtures. Variations in the stoichiometry of the films were achieved by altering the ratio of SiH4 to C3H8 flow rates at a sbstrate temperature in the range 240-260°C and total pressure between 30-70 mtorr. The silicon to carbon ratios were established by X-ray photoelectron spectroscopy, XPS, and the hydrogen content and distribution by infra-red spectroscopy.

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Valence band structure of hydrogenated amorphous silicon-carbon alloys studied by photoelectron spectroscopy

Physica B+C ◽

10.1016/0378-4363(83)90703-9 ◽

1983 ◽

Vol 117-118 ◽

pp. 947-949 ◽

Cited By ~ 8

Author(s):

Yoshifumi Katayama ◽

Toshikazu Shimada ◽

Keisuke L.I. Kobayashi ◽

Chang-gen Jiang ◽

Hiroshi Daimon ◽

...

Keyword(s):

Band Structure ◽

Amorphous Silicon ◽

Valence Band ◽

Photoelectron Spectroscopy ◽

Hydrogenated Amorphous Silicon ◽

Valence Band Structure ◽

Silicon Carbon ◽

Hydrogenated Amorphous

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Temperature and bias dependence of hydrogenated amorphous silicon – crystalline silicon heterojunction capacitance: the link to band bending and band offsets

Canadian Journal of Physics ◽

10.1139/cjp-2013-0544 ◽

2014 ◽

Vol 92 (7/8) ◽

pp. 690-695 ◽

Cited By ~ 2

Author(s):

O. Maslova ◽

A. Brézard-Oudot ◽

M.E. Gueunier-Farret ◽

J. Alvarez ◽

W. Favre ◽

...

Keyword(s):

Temperature Dependence ◽

Amorphous Silicon ◽

Crystalline Silicon ◽

Inversion Layer ◽

Hydrogenated Amorphous Silicon ◽

Analytical Calculation ◽

Diffusion Potential ◽

Band Offsets ◽

Strong Inversion ◽

Hydrogenated Amorphous

The temperature dependence of the capacitance–voltage data (C–V–T) of very high efficiency silicon heterojunction solar cells in a wide temperature range, up to 400 K, is analyzed. We show that the temperature dependence of the capacitance exhibits an anomalously large increase with temperature that cannot be explained under the usual depletion approximation. Using the complete analytical calculation of the capacitance, where the contribution of both types of carriers is taken into account, this large increase of capacitance with temperature of p-type hydrogenated amorphous silicon – n-type crystalline silicon ((p) a-Si:H – (n) c-Si) heterojunctions observed experimentally is reproduced. This increase of the capacitance is due to a strong inversion layer at the c-Si surface, which is promoted as the temperature increases. Further we show that the temperature dependence of the 1/C2 versus applied reverse voltage (Va) plot is as well strongly affected by the strong inversion layer at the c-Si surface. Consequently, the intercept of the linear extrapolation of 1/C2 versus Va with the voltage axis (Vint) differs significantly from the total diffusion potential predicted by depletion capacitance theory. These underestimated values of the total diffusion potential can consequently lead to erroneous estimation of the band offsets. The temperature dependence of Vint is considerably enhanced for the case of the full analytical calculation when compared with the depletion approximation approach. These data, obtained directly on the final solar cell device, thus confirm the existence of a surface strong inversion layer that was previously revealed by measurements performed by other techniques on dedicated or precursor devices, allowing one to get information on the band diagram and the heterointerface.

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