Study of the Influence of Structural Defects on Properties of Silicon Solar Cells

2013 ◽  
Vol 592-593 ◽  
pp. 449-452
Author(s):  
Jiří Šicner ◽  
Pavel Škarvada ◽  
Robert Macků ◽  
Pavel Koktavý

Solar cells of common sizes contains many of these defects and it is not easy to determine the influence of particular defects on the characteristics of the whole solar cell. Therefore, in our research we use samples of size of square centimeter at which we can disentangle the influence of the defect. We localize the defect by using a CCD camera, we measure the electrical, thermal and optical properties of the sample and then study it by means an electron microscope, we find the damaged structure and put it to focused ion beam. We expect the change in electrical, thermal and optical properties of the sample.

Author(s):  
B. Cunningham

IntroductionOne of the requirements for low-cost silicon solar cells is that the silicon substrates be relatively inexpensive (compared to standard Czochralski and float-zone wafers). This requirement has led to the development of a number of techniques for growing silicon ‘ribbons’, e.g. edge defined film-fed growth (EFG), silicon-on-ceramic (SOC), ribbon-to-ribbon (RTR) and dendritic web. Details of these and other growth techniques can be found in ref. Most of the growth methods produce silicon ribbons which contain relatively high densities of structural defects, such as grain boundaries, twin boundaries and dislocations. In addition, small amounts of chemical impurities are introduced into the ribbons during growth from sources such as shaping dies (EFG), substrates (SOC, RTR), heat shields, etc.


Author(s):  
Grigore Moldovan ◽  
Shark Lotharukpong ◽  
Peter Wilshaw

Abstract Electron Beam Induced Current (EBIC) characterization is unique in its ability to provide quantitative high-resolution imaging of electrical defects in solar cells. In particular, EBIC makes it possible to image electrical activity of single dislocations in a Dual-Beam Focused Ion Beam (FIB) Scanning Electron Microscope (SEM), to cut and lift out a micro-specimen containing a particular dislocation, and then transfer it for further structural or chemical analysis. As typical solar cell material presents a complex array of defects, it is important to observe statistical variations within a sample and select key sites for analysis. This paper describes a method for automated defect identification and characterization, and shows an application to multi-crystalline silicon (mc-Si) solar cell wafers selected from different heights along the manufactured ingot. Information presented here includes the experimental setup for data acquisition, as well as the basic algorithms used for identification and extraction of dislocation contrast.


2016 ◽  
Vol 258 ◽  
pp. 469-472
Author(s):  
Pavel Škarvada ◽  
Robert Macků ◽  
Lubomir Skvarenina

This paper investigates imperfection issues of Cu (In,Ga)Se2 thin-film solar cell structures and diagnostic methods of the CIGS solar cells. Electroluminescence and thermography are used to localize defect in macroscopic scale. Microstructures found in defective solar cell area are shown using micrographs. Focused ion beam was used to demonstrate that these structures interfere each solar cell layers. It is shown that micro sized defects (voids) behave as extra-stressed conductive channels that can degrade solar cells in module.


Author(s):  
E. Hendarto ◽  
S.L. Toh ◽  
J. Sudijono ◽  
P.K. Tan ◽  
H. Tan ◽  
...  

Abstract The scanning electron microscope (SEM) based nanoprobing technique has established itself as an indispensable failure analysis (FA) technique as technology nodes continue to shrink according to Moore's Law. Although it has its share of disadvantages, SEM-based nanoprobing is often preferred because of its advantages over other FA techniques such as focused ion beam in fault isolation. This paper presents the effectiveness of the nanoprobing technique in isolating nanoscale defects in three different cases in sub-100 nm devices: soft-fail defect caused by asymmetrical nickel silicide (NiSi) formation, hard-fail defect caused by abnormal NiSi formation leading to contact-poly short, and isolation of resistive contact in a large electrical test structure. Results suggest that the SEM based nanoprobing technique is particularly useful in identifying causes of soft-fails and plays a very important role in investigating the cause of hard-fails and improving device yield.


Author(s):  
H. J. Bender ◽  
R. A. Donaton

Abstract The characteristics of an organic low-k dielectric during investigation by focused ion beam (FIB) are discussed for the different FIB application modes: cross-section imaging, specimen preparation for transmission electron microscopy, and via milling for device modification. It is shown that the material is more stable under the ion beam than under the electron beam in the scanning electron microscope (SEM) or in the transmission electron microscope (TEM). The milling of the material by H2O vapor assistance is strongly enhanced. Also by applying XeF2 etching an enhanced milling rate can be obtained so that both the polymer layer and the intermediate oxides can be etched in a single step.


Author(s):  
Becky Holdford

Abstract On mechanically polished cross-sections, getting a surface adequate for high-resolution imaging is sometimes beyond the analyst’s ability, due to material smearing, chipping, polishing media chemical attack, etc.. A method has been developed to enable the focused ion beam (FIB) to re-face the section block and achieve a surface that can be imaged at high resolution in the scanning electron microscope (SEM).


Author(s):  
Julien Goxe ◽  
Béatrice Vanhuffel ◽  
Marie Castignolles ◽  
Thomas Zirilli

Abstract Passive Voltage Contrast (PVC) in a Scanning Electron Microscope (SEM) or a Focused Ion Beam (FIB) is a key Failure Analysis (FA) technique to highlight a leaky gate. The introduction of Silicon On Insulator (SOI) substrate in our recent automotive analog mixed-signal technology highlighted a new challenge: the Bottom Oxide (BOX) layer, by isolating the Silicon Active Area from the bulk made PVC technique less effective in finding leaky MOSFET gates. A solution involving sample preparation performed with standard FA toolset is proposed to enhance PVC on SOI substrate.


Author(s):  
Romaneh Jalilian ◽  
David Mudd ◽  
Neil Torrez ◽  
Jose Rivera ◽  
Mehdi M. Yazdanpanah ◽  
...  

Abstract The sample preparation for transmission electron microscope can be done using a method known as "lift-out". This paper demonstrates a method of using a silver-gallium nanoneedle array for a quicker sharpening process of tungsten probes with better sample viewing, covering the fabrication steps and performance of needle-tipped probes for lift-out process. First, an array of high aspect ratio silver-gallium nanoneedles was fabricated and coated to improve their conductivity and strength. Then, the nanoneedles were welded to a regular tungsten probe in the focused ion beam system at the desired angle, and used as a sharp probe for lift-out. The paper demonstrates the superior mechanical properties of crystalline silver-gallium metallic nanoneedles. Finally, a weldless lift-out process is described whereby a nano-fork gripper was fabricated by attaching two nanoneedles to a tungsten probe.


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