Publications de Antoine Descoeudres

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Plasma created during electrical discharge machining is systematically investigated using optical emission spectroscopy. Typical spectra show a strong H-alpha and continuum radiation, with many lines emitted by impurities coming from electrode and workpiece materials. The dielectric molecules are cracked by the discharge. Changing polarity affects the electrode wear and workpiece erosion rates, which can be qualitatively seen on the spectra. Time-resolved spectroscopy shows that the plasma density reaches 2

In amorphous/crystalline silicon heterojunction solar cells, optical losses can be mitigated by replacing the amorphous silicon films by wider bandgap amorphous silicon oxide layers. In this article, we use stacks of intrinsic amorphous silicon and amorpho ...

The current losses due to parasitic absorption in the indium tin oxide (ITO) and amorphous silicon (a-Si:H) layers at the front of silicon heterojunction solar cells are isolated and quantified. Quantum efficiency spectra of cells in which select layers are omitted reveal that the collection efficiency of carriers generated in the ITO and doped a-Si:H layers is zero, and only 30% of light absorbed in the intrinsic a-Si:H layer contributes to the shortcircuit current. Using the optical constants of each laye

Micro-particle formation in low pressure silane (SiH4) plasmas has been of technical interest and concern for at least 40 years. Negative ion plasma chemistry is a candidate for the initial nucleation, which has been extensively studied both experimentally ...

The plasma created during electrical discharge machining is investigated with imaging and spatially-resolved optical emission spectroscopy. Analysis of the pre-breakdown duration shows that the breakdown is of stochastic nature. Due to the presence of gas ...

The front transparent conductive oxide layer is a source of significant optical and electrical losses in silicon heterojunction solar cells because of the trade-off between free-carrier absorption and sheet resistance. We demonstrate that hydrogen-doped in ...

We report the results of scanning laser-beam-induced current (LBIC) measurements on silicon heterojunction solar cells that indicate the length scale over which photogenerated carriers are sensitive to local defects at the amorphous silicon/crystalline sil ...

Here high-efficiency (above 21%) large-area silicon heterojunction solar cells with atomic layer deposited ZnO:Al as front- or back-side transparent conducting oxide are demonstrated. Photoconductance decay measurements indicate that the excellent chemical ...

Electrical Discharge Machining (EDM) is a well-known machining technique since more than fifty years. Its principle is to use the eroding effect on the electrodes of successive electric spark discharges created in a dielectric liquid. EDM is nowadays widel ...

Reducing wafer thickness while increasing power conversion efficiency is the most effective way to reduce cost per Watt of a silicon photovoltaic module. Within the European project 20 percent efficiency on less than 100-mu m-thick, industrially feasible c ...

Silicon heterojunction solar cells have record-high open-circuit voltages but suffer from reduced short-circuit currents due in large part to parasitic absorption in the amorphous silicon, transparent conductive oxide (TCO), and metal layers. We previously identified and quantified visible and ultraviolet parasitic absorption in heterojunctions; here, we extend the analysis to infrared light in heterojunction solar cells with efficiencies exceeding 20%. An extensive experimental investigation of the TCO lay

Plasma created during EDM is systematically investigated with optical emission spectroscopy. Typical spectra show a strong H,,, and continuum radiation, with many lines emitted by impurities coming from electrode and workpiece materials. The dielectric molecules are cracked by the discharge. Time-resolved spectroscopy shows that the electron density is extreme at the beginning of the discharge. This causes merging of lines, strong Stark broadening and shift of the H,, line. The electron temperature is low a

In silicon heterojunction solar cells, the passivation of the crystalline silicon wafer surfaces and fabrication of emitter and back surface field are all performed by intrinsic and doped amorphous silicon thin layers, usually deposited by plasma-enhanced chemical vapor deposition (PECVD). Since the properties of materials deposited by PEVCD are directly linked to the plasma properties, plasma diagnostics are very useful tools to optimize such devices. A novel diagnostic has been developed to measure in-sit

A systematic comparison of front- and rear-emitter silicon heterojunction solar cells produced on nand p-type wafers was performed, in order to investigate their potential and limitations for high efficiencies. Cells on p-type wafers suffer from reduced minority carrier lifetime in the low-carrier-injection range, mainly due to the asymmetry in interface defect capture cross sections. This leads to slightly lower fill factors than for n-type cells. However, these losses can be minimized by using high-qualit

Silicon heterojunction solar cells are crystalline silicon-based devices in which thin amorphous silicon layers deposited on the wafer surfaces serve as passivated, carrier-selective contacts. The success of this technology is attributable to the ability o ...

The properties and high-efficiency potential of frontand rear-emitter silicon heterojunction solar cells on n- and p-type wafers were experimentally investigated. In the low-carrierinjection range, cells on p-type wafers suffer from reduced minority carrier lifetime, mainly due to the asymmetry in interface defect capture cross sections. This leads to slightly lower fill factors than for n-type cells. By using high-quality passivation layers, however, these losses can be minimized. High open-circuit voltage

In this contribution, we shortly review the main features of amorphous/crystalline silicon heterojunction (SHJ) solar cells, including interface defects and requirements for high quality interfaces. We show how a process flow with a limited number of proce ...

Attachment-induced ionization instability has been experimentally observed in O-2 and CF4 capacitive RF discharges using time-resolved voltage probe, Langmuir probe, optical emission and mass spectrometry measurements. This instability occurs under specific conditions of power and pressure, and produces synchronized oscillations in the kilohertz range on potentials, emission intensity and positive ion fluxes. In contrast, the SF6 plasma was observed to remain stable under all experimental conditions. This c

Damage of the hydrogenated amorphous/crystalline silicon interface passivation during transparent conductive oxide sputtering is reported. This occurs in the fabrication process of silicon heterojunction solar cells. We observe that this damage is at least partially caused by luminescence of the sputter plasma. Following low-temperature annealing, the electronic interface properties are recovered. However, the silicon-hydrogen configuration of the amorphous silicon film is permanently changed, as observed f

Silicon heterojunction solar cells have high open-circuit voltages thanks to excellent passivation of the wafer surfaces by thin intrinsic amorphous silicon (a-Si:H) layers deposited by plasma-enhanced chemical vapor deposition (PECVD). By using in-situ plasma diagnostics and ex-situ film characterization, we show that the best a-Si:H films for passivation are produced from deposition regimes close to the amorphous-to-crystalline transition. Based upon this finding, layers deposited in a large-area very hig

Antoine Descoeudres

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Optical emission spectroscopy of electrical discharge machining plasma

Amorphous silicon oxide window layers for high-efficiency silicon heterojunction solar cells

Current Losses at the Front of Silicon Heterojunction Solar Cells

Multiple dehydrogenation reactions of negative ions in low pressure silane plasma chemistry

Time-resolved imaging and spatially-resolved spectroscopy of electrical discharge machining plasma

Hydrogen-doped indium oxide/indium tin oxide bilayers for high-efficiency silicon heterojunction solar cells

Scanning Laser-Beam-Induced Current Measurements of Lateral Transport Near-Junction Defects in Silicon Heterojunction Solar Cells

Rear-emitter silicon heterojunction solar cells with atomic layer deposited ZnO:Al serving as an alternative transparent conducting oxide to In2O3:Sn

Characterization of electrical discharge machining plasmas

Manufacturing 100-mu m-thick silicon solar cells with efficiencies greater than 20% in a pilot production line

Infrared light management in high-efficiency silicon heterojunction and rear-passivated solar cells

Optical emission spectroscopy of electrical discharge machining plasma

Optimization of high efficiency silicon heterojunction solar cells using silane-plasma diagnostics

Silicon heterojunction solar cells on n- and p-type wafers with efficiencies above 20%

Amorphous Silicon/Crystalline Silicon Heterojunction Solar Cells

>21% Efficient Silicon Heterojunction Solar Cells on n- and p-Type Wafers Compared

A-Si:H/c-Si heterojunctions: a future mainstream technology for high-efficiency crystalline silicon solar cells ?

Attachment-induced ionization instability in electronegative capacitive RF discharges

Damage at hydrogenated amorphous/crystalline silicon interfaces by indium tin oxide overlayer sputtering

21% efficiency silicon heterojunction solar cells produced with very high frequency PECVD