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Kanti Jain - One of the best experts on this subject based on the ideXlab platform.
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patterning of single walled carbon nanotubes using a low fluence excimer laser photoAblation process
Applied Physics Letters, 2008Co-Authors: Junghun Chae, John A Rogers, Kanti JainAbstract:Carbon nanotube films were patterned by an excimer laser projection photoAblation process at low incident energy conditions. The carbon nanotubes were deposited on a quartz substrate and then a conventional photoresist was coated on it as a photoAblation assistor. The photoresist and the carbon nanotubes were simultaneously patterned by the projection photoAblation process, and then the photoresist was removed. It was possible to make clean patterns of carbon nanotubes even though the incident fluence on the carbon nanotubes was significantly lower than the threshold energy otherwise needed for their Direct Ablation.
Junghun Chae - One of the best experts on this subject based on the ideXlab platform.
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patterning of single walled carbon nanotubes using a low fluence excimer laser photoAblation process
Applied Physics Letters, 2008Co-Authors: Junghun Chae, John A Rogers, Kanti JainAbstract:Carbon nanotube films were patterned by an excimer laser projection photoAblation process at low incident energy conditions. The carbon nanotubes were deposited on a quartz substrate and then a conventional photoresist was coated on it as a photoAblation assistor. The photoresist and the carbon nanotubes were simultaneously patterned by the projection photoAblation process, and then the photoresist was removed. It was possible to make clean patterns of carbon nanotubes even though the incident fluence on the carbon nanotubes was significantly lower than the threshold energy otherwise needed for their Direct Ablation.
Heinz P. Huber - One of the best experts on this subject based on the ideXlab platform.
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Time and space resolved investigations of confined fs Ablation of Ta 2 O 5 /Pt thin film systems
Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XVIII, 2013Co-Authors: Stephan Rapp, Gerhard Heise, Janosch Rosenberger, Matthias Domke, Michael Schmidt, Heinz P. HuberAbstract:Maskless patterning of biocompatible sensor chips consisting of a Ta 2 O 5 /Pt/glass layer system can be realized by ultrashort laser pulse Ablation allowing fast and precise structuring. Here, a 650 fs laser at a center wavelength of 1053 nm is used at a peak fluence of 5 J/cm 2 . It was observed, that a greater diameter of the Pt film (400 nm) is ablated when it’s coated with Ta 2 O 5 (200 nm) compared to the uncoated Pt. One reason was found in the anti-reflective effect of the Ta 2 O 5 layer causing an increase of energy deposition in the material. The underlying physical effects of the Ablation reaction are investigated over the whole reaction time ranging temporally from fs to μs by ultrafast pump-probe microscopy. For the Direct Ablation of the uncoated Pt, results show ultrafast heating and melting after 2 ps, the creation of a gas-liquid mixture and plasma at 10 ps. At around 100 ns the actual Ablation takes place indicated by the ejection of small particles. The results for the Ta 2 O 5 /Pt layer system reveal heating and electron excitation in the Ta 2 O 5 layer during the first 2 ps. In the following the spot center behaves identical to the Direct Ablation of Pt. Here, the Ta 2 O 5 is ablated with the Pt. A confined Ablation where an additional amount of laser energy is deposited in the layer system or at the layer interface is assumed to take place. In the rim of the spot only the Ta 2 O 5 is removed by inDirectly-induced Ablation at around 35 ns.
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Investigation of the Ablation of zinc oxide thin films on copper–indium-selenide layers by ps laser pulses
Applied Physics A, 2011Co-Authors: Gerhard Heise, Marcel Dickmann, Andreas Heiss, Helmut Vogt, Matthias Domke, Thomas Kuznicki, Jörg Palm, Isabel Richter, Heinz P. HuberAbstract:The selective laser structuring of zinc oxide thin films, which serve as the transparent negative electrodes of copper–indium-selenide (CIS) thin film solar cells, is of great common interest as it can replace the mechanical scribing of the so-called pattern 3 (P3) process step for the monolithic serial interconnection of these cells. We present an investigation of the single-pulse Ablation behavior of zinc oxide thin films on glass substrates and on CIS layers and of trench scribing with 10-ps laser pulses at 1064 nm and at 532 nm. We show that the Ablation behavior strongly depends on the properties of the underling substrate and that the energy required to ablate a specific volume using induced laser processes (often referred to as ‘lift off’) is considerably reduced compared to the Direct Ablation of zinc oxide. With laser powers below 2 W at a wavelength of 1064 nm process speeds of 6 m/s for the P3 process have been achieved.
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investigation of the Ablation of zinc oxide thin films on copper indium selenide layers by ps laser pulses
Applied Physics A, 2011Co-Authors: Gerhard Heise, Marcel Dickmann, Andreas Heiss, Helmut Vogt, Matthias Domke, Thomas Kuznicki, Jörg Palm, Isabel Richter, Heinz P. HuberAbstract:The selective laser structuring of zinc oxide thin films, which serve as the transparent negative electrodes of copper–indium-selenide (CIS) thin film solar cells, is of great common interest as it can replace the mechanical scribing of the so-called pattern 3 (P3) process step for the monolithic serial interconnection of these cells. We present an investigation of the single-pulse Ablation behavior of zinc oxide thin films on glass substrates and on CIS layers and of trench scribing with 10-ps laser pulses at 1064 nm and at 532 nm. We show that the Ablation behavior strongly depends on the properties of the underling substrate and that the energy required to ablate a specific volume using induced laser processes (often referred to as ‘lift off’) is considerably reduced compared to the Direct Ablation of zinc oxide. With laser powers below 2 W at a wavelength of 1064 nm process speeds of 6 m/s for the P3 process have been achieved.
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Application of induced laser Ablation with ultra short pulse lasers for high speed thin film solar cell processing
International Congress on Applications of Lasers & Electro-Optics, 2010Co-Authors: Gerhard Heise, Marcel Dickmann, Jan Konrad, Isabell Richter, Sebastian Sarrach, Andreas Heiss, Helmut Vogt, Heinz P. HuberAbstract:The monolithic serial interconnection of CIS thin film solar cells is performed with ultra short pulse laser radiation @ 1064 nm. We present an investigation of induced laser processes (often referred as “lift-off”). We show that the energy required to ablate a specific volume using induced laser processes is considerably reduced compared to Direct Ablation processes and that less thermal damage is induced to surrounding material.Direct induced (separation of a molybdenum layer through the glass substrate, P1) and inDirect induced (transparent ZnO on absorbing CIS, P3) picosecond laser Ablation are not purely thermal processes working at energies per ablated volume far below the evaporation enthalpy. With laser powers below 2 W process speeds of 6 m/s for the P3 process and 4 m/s for the P1 process have been achieved.The monolithic serial interconnection of CIS thin film solar cells is performed with ultra short pulse laser radiation @ 1064 nm. We present an investigation of induced laser processes (often referred as “lift-off”). We show that the energy required to ablate a specific volume using induced laser processes is considerably reduced compared to Direct Ablation processes and that less thermal damage is induced to surrounding material.Direct induced (separation of a molybdenum layer through the glass substrate, P1) and inDirect induced (transparent ZnO on absorbing CIS, P3) picosecond laser Ablation are not purely thermal processes working at energies per ablated volume far below the evaporation enthalpy. With laser powers below 2 W process speeds of 6 m/s for the P3 process and 4 m/s for the P1 process have been achieved.
W.h. Zhu - One of the best experts on this subject based on the ideXlab platform.
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Laser-induced shock waves in PMMA confined foils
International Journal of Impact Engineering, 2000Co-Authors: W.h. ZhuAbstract:Abstract Confined Ablation experiments were performed to measure pulsed laser-induced shock wave profiles in aluminum and copper foils by using polyvinylidene fluoride (PVDF) gauges. The aluminum and copper targets of 40–200 μm thickness were irradiated by neodymium laser at 1.06 μm wavelength and at a pulse width of 33 ns (FWHM, full-width at half-maximum) at a power density around 0.45 G W/cm2. A 3 mm thick polymethyl methacrylate (PMMA) overlay was used to confine the target. Experimental measurements revealed the dependence of the laser-induced shock pressure on the thickness and material properties of the target. It was found that attenuation of peak pressure of the laser-induced shock waves could be well fitted by a power-form function P M =P 0 X −n . Here, n is a parameter relevant to material properties, P 0 is the pressure when X=1 and P M is the maximum pressure at X , the propagation distance of the shock wave from the front surface of the target. A simplified analytical description is presented to illustrate the features of the shock profiles obtained from experiments. The space–time diagram of wave propagation and the successive pressure states were determined from which theoretical pressure time profiles were constructed. Both the experiment and theoretical analysis inferred a shock pressure of 4.5–5.5 kbar in the target. Some Direct Ablation experiments were also conducted to evaluate the enhancement of pressure for PMMA confinement. By comparison with Direct Ablation, confined Ablation can increase the pressure by 7.5–11.8 times. The study provides the data for the PMMA-confined targets.
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Laser-induced shock waves in PMMA confined foils
International Journal of Impact Engineering, 2000Co-Authors: W.h. ZhuAbstract:Confined Ablation experiments were performed to measure pulsed laser-induced shock wave profiles in aluminum and copper foils by using polyvinylidene fluoride (PVDF) gauges. The aluminum and copper targets of 40-200 mu m thickness were irradiated by neodymium laser at 1.06 mu m wavelength and at a pulse width of 33 ns (FWHM, full-width at half-maximum) at a power density around 0.45 G W/cm(2). A 3 mm thick polymethyl methacrylate (PMMA) overlay was used to confine the target. Experimental measurements revealed the dependence of the laser-induced shock pressure on the thickness and material properties of the target. It was found that attenuation of peak pressure of the laser-induced shock waves could be well fitted by a power-form function P-M = P0X-n. Here, n is a parameter relevant to material properties, P-0 is the pressure when X = 1 and P-M is the maximum pressure at X, the propagation distance of the shock wave from the front surface of the target. A simplified analytical description is presented to illustrate the features of the shock profiles obtained from experiments. The space-time diagram of wave propagation and the successive pressure states were determined from which theoretical pressure time profiles were constructed. Both the experiment and theoretical analysis inferred a shock pressure of 4.5-5.5 kbar in the target. Some Direct Ablation experiments were also conducted to evaluate the enhancement of pressure for PMMA confinement. By comparison with Direct Ablation, confined Ablation can increase the pressure by 7.5-11.8 times. The study provides the data for the PMMA-confined targets. (C) 2000 Elsevier Science Ltd. All rights reserved
John A Rogers - One of the best experts on this subject based on the ideXlab platform.
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patterning of single walled carbon nanotubes using a low fluence excimer laser photoAblation process
Applied Physics Letters, 2008Co-Authors: Junghun Chae, John A Rogers, Kanti JainAbstract:Carbon nanotube films were patterned by an excimer laser projection photoAblation process at low incident energy conditions. The carbon nanotubes were deposited on a quartz substrate and then a conventional photoresist was coated on it as a photoAblation assistor. The photoresist and the carbon nanotubes were simultaneously patterned by the projection photoAblation process, and then the photoresist was removed. It was possible to make clean patterns of carbon nanotubes even though the incident fluence on the carbon nanotubes was significantly lower than the threshold energy otherwise needed for their Direct Ablation.