Cadmium Chloride Assisted Re-Crystallization of CdTe: The Effect of Varying the Annealing Time

2014 ◽  
Vol 1638 ◽  
Author(s):  
A. Abbas ◽  
G. D. West ◽  
J.W. Bowers ◽  
P. M. Kaminski ◽  
B. Maniscalco ◽  
...  
Keyword(s):  
Cadmium Telluride ◽  
Cadmium Chloride ◽  
High Efficiency ◽  
Morphological Changes ◽  
Depth Profiling ◽  
Annealing Treatment ◽  
Photovoltaic Devices ◽  
Micro Structure ◽  
Transmission Electron ◽  
Chloride Treatment

ABSTRACTAlthough the cadmium chloride treatment is an essential process for high efficiency thin film cadmium telluride photovoltaic devices, the precise mechanisms involved that improve the cadmium telluride layer are not well understood. In this investigation we apply advanced micro-structural characterization techniques to study the effect of varying the time of the cadmium chloride annealing treatment on the micro-structure of cadmium telluride solar cells deposited by close spaced sublimation (CSS) and relate this to cell performance. A range of techniques has been used to observe the morphological changes to the micro-structure as well as the chemical and crystallographic changes as a function of treatment parameters. Electrical tests that link the device performance with the micro-structural properties of the cells have also been undertaken. Techniques used include Transmission Electron Microscopy (TEM) for sub-grain analysis and XPS for composition-depth profiling. The study provides a new insight in to the mechanisms involved in the initiation and the subsequent complete re-crystallization of the cadmium telluride layer.

The Effect of Annealing Treatments on Close Spaced Sublimated Cadmium Telluride Thin Film Solar Cells

2013 ◽  
Vol 1493 ◽  
pp. 147-152 ◽  
Author(s):  
J.M. Walls ◽  
A. Abbas ◽  
G. D. West ◽  
J.W. Bowers ◽  
P.J.M. Isherwood ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Cadmium Telluride ◽  
Cadmium Chloride ◽  
High Efficiency ◽  
Stacking Faults ◽  
Annealing Treatment ◽  
Complete Removal ◽  
Close Space Sublimation ◽  
Transmission Electron

ABSTRACTIt is well known that the cadmium chloride annealing treatment is an essential step in the manufacture of efficient thin film cadmium telluride solar cells. It has been recognized that the combination of annealing at ∼4000C together with the addition of cadmium chloride at the surface induces re-crystallisation of the cadmium telluride layer and also affects the n-type cadmium sulfide. We have applied advanced micro-structural characterization techniques to distinguish the effect of the annealing and the cadmium chloride treatments on the properties of the cadmium telluride deposited via close space sublimation (CSS) and relate these observations to device performance. Transmission electron microscopy (TEM) has shown a variation in stacking fault density with annealing temperature and annealing time. Stacking faults observed within the cadmium telluride grains in TEM were partially removed post annealing; these findings show that temperature alone has a role in the reduction of stacking faults. However, since we have previously observed almost complete removal of stacking faults with annealing in combination with cadmium chloride, the cadmium chloride is essential to defect removal and high efficiency cells.

3D Distributions of Chlorine and Sulphur Impurities in a Thin-Film Cadmium Telluride Solar Cell

MRS Advances ◽  
2018 ◽  
Vol 3 (56) ◽  
pp. 3287-3292 ◽  
Author(s):  
Thomas A. M. Fiducia ◽  
Kexue Li ◽  
Amit H. Munshi ◽  
Kurt Barth ◽  
Walajabad S. Sampath ◽  
...  
Keyword(s):  
Cadmium Telluride ◽  
Cadmium Chloride ◽  
High Efficiency ◽  
Cadmium Sulphide ◽  
Diffusion Profile ◽  
Lattice Diffusion ◽  
Three Dimensions ◽  
Device Performance ◽  
Extended Defects ◽  
Cdte Solar Cells

ABSTRACTA cadmium chloride activation treatment is essential for the production of high efficiency cadmium telluride (CdTe) solar cells. However, the effects of the treatment on the distributions of chlorine and sulphur within the device are not fully understood. Here, the detailed locations of chlorine and sulphur in a treated CdTe cell are determined in three dimensions by high resolution dynamic SIMS measurements. Chlorine is found to be present in grain boundaries, grain interiors, extended defects within the grain interiors, at the front interface, and in the cadmium sulphide layer. In each of these regions, the chlorine is likely to have significant effects on local electronic properties of the material, and hence overall device performance. Sulphur is found to have a U-shaped diffusion profile within CdTe grains, indicating a mixed grain boundary and lattice diffusion regime.

An EELS-Study of the Chemical Homogeneity in Cu-In-S Films

1999 ◽  
Vol 5 (S2) ◽  
pp. 636-637
Author(s):  
D.S. Su ◽  
P. Schattschneider ◽  
E. Zeitler
Keyword(s):  
Electron Microscope ◽  
High Efficiency ◽  
Incident Angle ◽  
Photovoltaic Devices ◽  
Ion Milling ◽  
Si Substrate ◽  
Electron Microscopic ◽  
Chemical Homogeneity ◽  
Transmission Electron ◽  
Ternary Chalcopyrites

The development of high-efficiency, low-price photovoltaic devices relies on epitaxially grown layers of ternary chalcopyrites. The question addressed in this study is to which extent the near stoichimetric composition of CuInS2 grown on hydrogen terminated Silicon, Si (111), varies cross the sample area. The method usually employed [1] for such analysis is Argon-Rutherford Backscattering (RBS), whose spatial resolution, however, is limited to the order of millimeters. This limit can readily be overcome by electron microscopic and electron spectroscopic means.For observation and recording of the energy loss spectra in the transmission electron microscope, samples were carefully prepared by mechanic polishing and ion-milling. The thinning began with polishing the Si substrate on ALLED diamond lapping films, down to 10 μm and a final ion-milling in a Gatan ion-thinning equipment from the Si-side (Ar+ 3 kV, the incident angle less than 7°).Spectra were taken by means of a Gatan image filter (GIF - 100) in a Philips CM200 FEG electron microscope operated at 200 kV.

scholarly journals The Effect of Cadmium Chloride Treatment on Close-Spaced Sublimated Cadmium Telluride Thin-Film Solar Cells

2013 ◽  
Vol 3 (4) ◽  
pp. 1361-1366 ◽  
Author(s):  
A. Abbas ◽  
G. D. West ◽  
J. W. Bowers ◽  
P. Isherwood ◽  
P. M. Kaminski ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Cadmium Telluride ◽  
Cadmium Chloride ◽  
Thin Film Solar Cells ◽  
Chloride Treatment

scholarly journals Cadmium Chloride Assisted Re-Crystallisation of CdTe: The Effect on the CdS Window Layer

2015 ◽  
Vol 1738 ◽  
Author(s):  
Ali Abbas ◽  
Piotr Kaminski ◽  
Geoff West ◽  
Kurt Barth ◽  
WS Sampath ◽  
...  
Keyword(s):  
Cadmium Chloride ◽  
Density Functional ◽  
Treatment Time ◽  
Depth Profiling ◽  
Stacking Faults ◽  
Annealing Treatment ◽  
Cadmium Sulphide ◽  
Window Layer ◽  
Electrical Performance ◽  
Cell Efficiency

ABSTRACTThe cadmium chloride annealing treatment is an essential step in the manufacture of efficient thin film CdTe solar cells. In previous work we have shown that the primary effect of the treatment is to remove high densities of stacking faults from the as-deposited material. Use of density functional theory has shown that some of the higher energy stacking faults are hole traps. Removal of these defects dramatically improves cell efficiency. In this study we focus on the effect of the activation treatment on the underlying n-type cadmium sulphide layer. A range of techniques has been used to observe the changes to the microstructure as well as the chemical and crystallographic changes as a function of treatment parameters. Electrical tests that link the device performance with the micro-structural properties of the cells have also been undertaken. Techniques used include High Resolution Transmission Electron Microscopy (HRTEM) for sub-grain analysis, EDX for chemical analysis and XPS and SIMS for composition-depth profiling. By studying the effect of increasing the treatment time and temperature, we will show that the cadmium sulphide layer depletes to the point of complete dissolution into the absorber layer. We will also show that chlorine penetrates and decorates the grain boundaries in the cadmium sulphide. In addition we will show that chlorine builds up at the heterojunction and concentrates in voids at the cadmium telluride/cadmium sulphide interface. A combination of these effects damages the electrical performance of the solar cell.

Atom Probe Analysis of III–V and Si-Based Semiconductor Photovoltaic Structures

2007 ◽  
Vol 13 (6) ◽  
pp. 493-502 ◽  
Author(s):  
Brian P. Gorman ◽  
Andrew G. Norman ◽  
Yanfa Yan
Keyword(s):  
High Efficiency ◽  
Low Cost ◽  
Depth Profiling ◽  
Compositional Analysis ◽  
Atom Probe ◽  
Photovoltaic Devices ◽  
Chemical Profiling ◽  
Semiconductor Conductivity

The applicability of atom probe to the characterization of photovoltaic devices is presented with special emphasis on high efficiency III–V and low cost ITO/a-Si:H heterojunction cells. Laser pulsed atom probe is shown to enable subnanometer chemical and structural depth profiling of interfaces in III–V heterojunction cells. Hydrogen, oxygen, and phosphorus chemical profiling in 5-nm-thick a-Si heterojunction cells is also illustrated, along with compositional analysis of the ITO/a-Si interface. Detection limits of atom probe tomography useful to semiconductor devices are also discussed. Gaining information about interfacial abruptness, roughness, and dopant profiles will allow for the determination of semiconductor conductivity, junction depletion widths, and ultimately photocurrent collection efficiencies and fill factors.

Imaging and diffraction modes in Scanning Transmission Electron Microscopy

1986 ◽  
Vol 44 ◽  
pp. 684-687
Author(s):  
J. M. Cowley ◽  
R. Glaisher ◽  
J. A. Lin ◽  
H.-J. Ou
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
High Efficiency ◽  
Fiber Optic ◽  
Image Intensifier ◽  
Detector System ◽  
Detector Plane ◽  
Secondary Electrons ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Special Detector

Some of the most important applications of STEM depend on the variety of imaging and diffraction made possible by the versatility of the detector system and the serial nature, of the image acquisition. A special detector system, previously described, has been added to our STEM instrument to allow us to take full advantage of this versatility. In this, the diffraction pattern in the detector plane may be formed on either of two phosphor screens, one with P47 (very fast) phosphor and the other with P20 (high efficiency) phosphor. The light from the phosphor is conveyed through a fiber-optic rod to an image intensifier and TV system and may be photographed, recorded on videotape, or stored digitally on a frame store. The P47 screen has a hole through it to allow electrons to enter a Gatan EELS spectrometer. Recently a modified SEM detector has been added so that high resolution (10Å) imaging with secondary electrons may be used in conjunction with other modes.

Ultrastructural Study of Rat Colon Following Psyllium Ingestion

1985 ◽  
Vol 43 ◽  
pp. 580-581
Author(s):  
F.G. Lightfoot ◽  
L.E. Grau ◽  
M.M. Cassidy ◽  
G.R. Tadvalkar ◽  
G.V. Vahouny
Keyword(s):  
Electron Microscopy ◽  
Morphological Changes ◽  
Large Population ◽  
Rat Colon ◽  
Gastrointestinal Disorders ◽  
Luminal Surface ◽  
Fecal Material ◽  
Transmission Electron ◽  
Morphologic Analysis ◽  
Irritable Bowel

Psyllium hydrophillic mucilloid is a natural gelling fiber consumed by a large population of our society. It is used as a bulk-producing laxative and in the treatment of gastrointestinal disorders such as “Irritable Bowel Syndrome”. The literature pertaining to the ultrastructural effects of this agent is sparse.This study documents morphological changes induced by psyllium. Animals fed a diet containing 2% psyllium for four weeks were subsequently sacrificed and processed for scanning and transmission electron microscopy. The colon contained fecal material combined with psyllium which conformed to the contour of the luminal surface. This mixture formed surface replicas of the intestinal mucosa. These replicas and their related colonic sites were processed for morphologic analysis.

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