Characterization of Electrical Contacts on Silicon (100) after Ablation and Sulfur Doping by Femtosecond Laser Pulses

2013 ◽  
Vol 205-206 ◽  
pp. 358-363 ◽  
Author(s):  
Philipp Saring ◽  
Anna Lena Baumann ◽  
Stefan Kontermann ◽  
Wolfgang Schade ◽  
Michael Seibt

This paper investigates the influence of different number of laser pulses on contact behavior and conductivity of the surface layer of femtosecond laser microstructured, sulfur-doped silicon. Single shot laser processed silicon (Pink Silicon) is characterized by low surface roughness, whereas five shot laser processed silicon (Grey Silicon) has an elevated sulfur content with a surface roughness low enough to maintain good contacting. To laterally confine the laser induced pn-junction part of the Grey Silicon sample surface is etched off. The etching depth is confirmed to be sufficient to completely remove the active n-type sulfur layer. While Pink Silicon shows little or no lateral conductivity within the laser processed layer, Grey Silicon offers acceptable conductivity, just as expected by the fact of having incorporated a higher sulfur dopant content. Recombination dominates the irradiated regions of Pink Silicon and suppresses excess charge carrier collection. Grey Silicon, while showing sufficient lateral conductivity, still shows regions of lower conductivity, most likely dominated by the laser irradiation-induced formation of dislocations. According to our results, the optimum laser pulse number for electrical and structural properties is expected to be in the range between one and five laser pulses.

2015 ◽  
Vol 752-753 ◽  
pp. 452-457
Author(s):  
Michael Babiy ◽  
Yuliya Biryukova ◽  
Sergey Golik ◽  
Vladimir Lisitsa

The result of direct ablation of silicon by an 800 nm Ti:Sa femtosecond laser pulses are presented. Obtained slice of silicon with submicron roughness with tilt focused femtosecond laser pulses. Yaw cut more due to mechanical vibrations of the entire installation on a pneumatic table, but not the physics of the ongoing process. During processing, possibly thinning the silicon sample from the opposite edge (sharpening) to submicron values ​​(tens of nanometers).


Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1093
Author(s):  
Evaldas Kažukauskas ◽  
Simas Butkus ◽  
Piotr Tokarski ◽  
Vytautas Jukna ◽  
Martynas Barkauskas ◽  
...  

Biocompatible polymers are used for many different purposes (catheters, artificial heart components, dentistry products, etc.). An important field for biocompatible polymers is the production of vision implants known as intraocular lenses or custom-shape contact lenses. Typically, curved surfaces are manufactured by mechanical means such as milling, turning or lathe cutting. The 2.5 D objects/surfaces can also be manufactured by means of laser micromachining; however, due to the nature of light–matter interaction, it is difficult to produce a surface finish with surface roughness values lower than ~1 µm Ra. Therefore, laser micromachining alone can’t produce the final parts with optical-grade quality. Laser machined surfaces may be polished via mechanical methods; however, the process may take up to several days, which makes the production of implants economically challenging. The aim of this study is the investigation of the polishing capabilities of rough (~1 µm Ra) hydrophilic acrylic surfaces using bursts of femtosecond laser pulses. By changing different laser parameters, it was possible to find a regime where the surface roughness can be minimized to 18 nm Ra, while the polishing of the entire part takes a matter of seconds. The produced surface demonstrates a transparent appearance and the process shows great promise towards commercial fabrication of low surface roughness custom-shape optics.


2011 ◽  
Vol 142 ◽  
pp. 134-137
Author(s):  
Hong Yun Chen ◽  
Zhen Zhu Wan ◽  
Yan Ling Han

The interaction between femtoseocnd laser and transparent materials has been studied intensively in recent years. When the femtosecond laser was focused onto the surface of the transparent materials, if the laser fluence applied to the sample exceeds the material’s fluence threshold, ablation occurs. In this paper, we study the surface ablation of lithium niobate by femtosecond laser. We produced a two-dimensional array of voids in the sample surface by varying the number of shots and laser energy, and analyze of the damage depth with the relation to the pulse energy and the number of the pulse. It has important reference on the microfabrication in such materials by femtosecond laser.


2000 ◽  
Vol 6 (2) ◽  
pp. 143-152 ◽  
Author(s):  
R. Heinicke ◽  
C. Grun ◽  
J. Grotemeyer

Measurements of a single shot femtosecond laser pump-probe technique on substituted benzalacetones are reported. The technique is based on counter propagating femtosecond laser pulses in a supersonic beam of low density of sample molecules and simultaneous probe detection by ion or fragment ion formation through a reflectron time-of-flight mass spectrometer. It will be shown that the range of the pump-probe delays covers the time span between 100 fs and 10 ps depending on the pulse width of the laser used and the stability of the voltages of the mass spectrometer. The application of this technique to medium-sized organic molecules reveals some insight into the electron transfer process during ionisation through a 1 + 1 multi-photon absorption procedure. Furthermore it is demonstrated that this technique is also applicable to the investigation of ultra-fast isomerisation and fragmentation processes.


2004 ◽  
Vol 43 (3) ◽  
pp. 993-996 ◽  
Author(s):  
Katsutoshi Takatoi ◽  
Akira Suda ◽  
Yu Oishi ◽  
Pengqian Wang ◽  
Keigo Nagasaka ◽  
...  

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