MKS Instruments (United States)

Tunnel oxide passivated contact (TOPCon) solar cells will likely become the most produced crystalline silicon photovoltaic architecture within the next five years. The technology relies on multiple thin films to improve cell efficiency by further reducing electron-hole recombination at metal-semiconductor interfaces. Lasers are used to remove the anti-reflection thin film layer to prepare regions of the cells for electrical contact formation (“metallization”). This process—laser contact opening or LCO—is challenging in that the underlying thin films must suffer minimal damage. TOPCon is an ideal architecture for implementing electrochemical plating metallization, which has certain advantages over conventional methods. In this work we report on the use of ultraviolet (UV) wavelength ultrashort pulse lasers for TOPCon LCO processing in concert with electrochemical plating metallization. Laser parameters selection is reviewed, and processing results are analyzed with optical and scanning electron microscopy. Complete solar cells are fabricated and performance metrics are discussed.

Magnetic components significantly impact the performance and size of power electronic circuits. This is especially true at radio frequencies (RF) of many MHz and above. In the high-frequency (HF, 3-30 MHz) range, coreless (or “air-core”) inductors are conventionally used. These inductors have typical quality factors (Qs) of 200-500. However, their uncontrolled magnetic fields can induce electromagnetic interference (EMI) and eddy current losses in surrounding components, limiting system miniaturization. This makes them a major contributor to overall system loss and size. With recent advances in high-frequency magnetic materials, there is interest in design of cored inductors to achieve improved combinations of size and loss. This work investigates an approach to achieving high-power, high-frequency, high-Q cored inductors. The proposed design approach leverages high-frequency magnetic materials, core geometry, quasi-distributed gaps, and a copper shield to realize high-frequency inductors that emit little f lux outside their physical volume. Design guidelines for such inductors are introduced and experimentally verified with a 155 kVA, 570 nH inductor (Q = 1150) designed to operate at 13.56 MHz with a peak ac current of up to 80 Amps. A high-efficiency and compact back-to-back L-match is used to demonstrate the high-performance and self-shielding capability of this prototype inductor.

Abstract A detailled study of the impact of stereoelectronic effects of olefins in the Matsuda‐Heck‐reaction was addressed by kinetic studies. In addition to the stereoelectronic effects of the olefins used, their influence on the formation of the catalytic Pd colloids was also investigated. Depending on the olefin used, different particle size distributions were obtained on the one hand and, on the other hand, inhibition effects due to adsorption of the olefins on the Pd colloids were observed. Based on these findings, it was possible to optimize reaction conditions for the respective olefins. The presented kinetic data were supplemented by STEM‐measurements.

As communication networks move toward higher frequency bands, thin glass substrates are advancing toward industrial production in packaging and interconnect applications as high-frequency, low-loss materials. While current techniques for the formation of through glass vias (TGVs) allow for efficient drilling of <40 μm diameter holes, there are currently limited commercially viable options for smaller TGVs. Presented herein is a unique approach to forming high aspect ratio TGVs in 10-20 μs for 50 and 100 μm thick glass. This is accomplished by using a high-power quasi-continuous wave (QCW) laser with a simple Gaussian beam profile focusing scheme. Crucially, this approach is compatible with high bandwidth beam steering technologies, i.e., the combination of galvanometers and acousto-optic deflectors (AODs), allowing for simple scaling to industrially viable throughputs of tens of thousands of vias per second for high-density drill patterns. The TGVs have straight, smooth sidewalls, and high uniformity. Birefringence image microscopy is used to further assess the finer quality aspects of the TGVs formed; considerable residual stress embedded around the TGVs was found after laser drilling, which could cause cracking in subsequent process steps. It is demonstrated that the stress can be significantly reduced by either annealing the glass substrate after drilling or drilling at elevated temperatures to mitigate the embedded stress.

This joint issue of Optics Express and Optical Materials Express features 17 state-of-the art articles written by authors who participated in the international conference Advanced Solid-State Lasers held in Vienna, Austria, from September 29 to October 3, 2019. This introduction provides a summary of these articles that cover numerous areas of solid-state lasers from materials research to sources and from design to experimental demonstration.

Theoretical analysis suggests that decentralized active vibration damping implementing skyhook control (or advanced versions thereof), while applied locally, reduces vibration level over the whole structure by introducing modal damping. That was, however, never directly confirmed experimentally. Laser vibrometry, measuring vibration in multiple points in quick succession and referencing it to the excitation force, provides this opportunity. This paper reports theoretical considerations and experimental results illustrating reduction of total kinetic energy of all-steel optical breadboard by two active dampers. It had been shown (S. Elliott et al.) that the effect of collocated decentralized vibration control is limited by two phenomena: instability and “pinning.” These issues are analyzed by direct measurement of kinetic energy for a range of active control gains. Optimal gains minimizing kinetic energy with sufficient stability margin are demonstrated and discussed.

Person Re-identification has been a widely explored topic in automated video-based surveillance. Nonetheless, the substantial body of work in this area deals only with upright images of persons captured using rectilinear lenses. However, for surveillance applications, it is often preferable to use fisheye lenses to expand the field of view. Person re-identification using fisheye lenses is an uncharted territory with potential applications in image and video-based surveillance. In this paper, we explore various techniques by which we can use images and videos captured by fisheye lenses for person re-identification using conventional algorithms developed for rectilinear images. We discuss the application of foreground extraction and propose a framework for orientation normalization for use in fisheye images. We also introduce a novel radial co-location search to improve the accuracy of person re-identification using fisheye lenses.

Vibration damping of honeycomb optical tables had been subject of significant research and development efforts during several decades. These efforts resulted in tuned and broadband damping treatments, as well as active damping systems that found extensive practical applications. Smaller optical platforms (breadboards) are often used for vibration-sensitive applications due to dearth of laboratory space and increased sensitivity of small optical instruments. Relatively massive damping devices that work for large tables are not applicable to smaller (usually up to about 10 cm thick) breadboards. This paper describes a new method for damping resonance vibration of optical breadboards with honeycomb cores. The method makes use of modal geometry of orthotropic laminated plates by integrating a layer of highly damped material between two surfaces making it to work in shear. Physical principle, optimization procedure, practical designs, implementation and test results of damped breadboards are presented.

Control of ion energy distributions (IEDs) onto the surface of wafers is an ongoing challenge in microelectronics fabrication. The use of capacitively coupled plasmas (CCPs) using multiple radio frequency (rf) power sources provides many opportunities to customize IEDs. In dual-frequency CCPs using a fundamental frequency and its second harmonic, varying the relative voltages, powers, and phases between the fundamental and second harmonic biases have demonstrated potential as control mechanisms for the shape of the IEDs. In this paper, we report on computational and experimental investigations of IED control in dual-frequency and triple-frequency CCPs where the phase between the fundamental and second harmonic frequency voltage waveform is used as a control variable. The operating conditions were 5–40 mTorr (0.67–5.33 Pa) in Ar and Ar/CF4/O2 gas mixtures. By changing the phase between the applied rf frequency and its second harmonic, the Electrical Asymmetric Effects was significant and not only shifted the dc self-bias but also affected plasma uniformity. When changing phases of higher harmonics, the energies and widths of the IEDs could be controlled. With the addition of a 3rd high-frequency source, the plasma density increased and uniformity improved. Computed results for IEDs were compared with experimental results using an ion energy analyzer in systems using rf phase locked power supplies.