Preparation of Large Area Cross-Sectional Tem Specimen of Semiconducting Heteroepitaxial Materials

1991 ◽  
Vol 254 ◽  
Author(s):  
M. Tamura ◽  
S. Aoki
Keyword(s):  
Sample Preparation ◽  
Film Growth ◽  
General Information ◽  
One Dimension ◽  
Main Principle ◽  
Large Area ◽  
Cross Sectional ◽  
Growth Modes ◽  
Present Technique ◽  
Grinding And Polishing

AbstractThe sample preparation procedures which enable us to observe large areas over a few tens of microns in one-dimension of semiconducting heteroepitaxial materials are described. The main principle involves the careful grinding and polishing of samples. In these procedures, another side thinning of the specimen after finishing initial side polishing is carried out using a sample platform by hand throughout all of the following steps. It is shown that for some typical examples of heteroepitaxial films general information concerning the film growth modes and structures, as well as the defect morphologies and natures introduced during growth can be effectively obtained by using the present technique.

The Use of AlN Interlayers to Improve GaN Growth on A-Plane Sapphire

1999 ◽  
Vol 587 ◽  
Author(s):  
D.D. Koleske ◽  
M.E. Twigg ◽  
A.E. Wickenden ◽  
R.L. Henry ◽  
R.J. Gorman ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Screw Dislocation ◽  
Film Growth ◽  
Fold Increase ◽  
Large Area ◽  
Cross Sectional ◽  
Acceptor Concentration ◽  
Si Doped ◽  
Gan Film ◽  
Screw Dislocation Density

AbstractThe lack of a suitable, lattice matched substrate for the growth of the group III nitrides typically restricts GaN film growth to substrates such as sapphire or SiC, despite the large lattice and thermal mismatch. With the use of AlN or GaN nucleation layers (NL), GaN films of sufficient quality have been produced for blue LEDs. However, for laser and large-area microwave device applications, the large number of dislocations (> 108 cm−2) limit device performance, and techniques are desired to reduce dislocation density during the growth process. Here, we demonstrate how low temperature AlN interlayers (IL) sandwiched between high temperature (HT) GaN layers can be used to improve the electrical, optical, and structural properties of Si doped GaN films. A nearly two-fold increase in mobility is observed in Si doped GaN grown using 5 AlN IL compared to GaN grown on a single AlN NL. For GaN films grown on multiple AlN IL, cross-sectional transmission electron microscopy images reveal a significant reduction in the screw dislocation density and photoluminescence spectra reveal a reduction in yellow band intensity. An analysis of the electrical data based on a single donor/single acceptor model suggests that the improved electron mobility is the result of a reduced acceptor concentration in the top GaN film. The reduction in the calculated acceptor concentration may be associated with the reduction of the screw dislocation density.

TEM sample preparation of wear-tested room-temperature pulsed-laser-deposited thin films of MoS2 by ultramicrotomy

1993 ◽  
Vol 51 ◽  
pp. 1118-1119
Author(s):  
Pamela F. Lloyd ◽  
Scott D. Walck
Keyword(s):  
Thin Films ◽  
Sample Preparation ◽  
Room Temperature ◽  
High Vacuum ◽  
Pulsed Laser ◽  
Ultra High Vacuum ◽  
Wear Testing ◽  
Preparation Technique ◽  
Cross Sectional ◽  
Aerospace Applications

Pulsed laser deposition (PLD) is a novel technique for the deposition of tribological thin films. MoS2 is the archetypical solid lubricant material for aerospace applications. It provides a low coefficient of friction from cryogenic temperatures to about 350°C and can be used in ultra high vacuum environments. The TEM is ideally suited for studying the microstructural and tribo-chemical changes that occur during wear. The normal cross sectional TEM sample preparation method does not work well because the material’s lubricity causes the sandwich to separate. Walck et al. deposited MoS2 through a mesh mask which gave suitable results for as-deposited films, but the discontinuous nature of the film is unsuitable for wear-testing. To investigate wear-tested, room temperature (RT) PLD MoS2 films, the sample preparation technique of Heuer and Howitt was adapted.Two 300 run thick films were deposited on single crystal NaCl substrates. One was wear-tested on a ball-on-disk tribometer using a 30 gm load at 150 rpm for one minute, and subsequently coated with a heavy layer of evaporated gold.

TEM Sample Preparation Tricks for Advanced DRAMs

2015 ◽  
Author(s):  
Ching Shan Sung ◽  
Hsiu Ting Lee ◽  
Jian Shing Luo
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Sample Preparation ◽  
Integrated Circuit ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Tem Analysis ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Characterization Of Materials

Abstract Transmission electron microscopy (TEM) plays an important role in the structural analysis and characterization of materials for process evaluation and failure analysis in the integrated circuit (IC) industry as device shrinkage continues. It is well known that a high quality TEM sample is one of the keys which enables to facilitate successful TEM analysis. This paper demonstrates a few examples to show the tricks on positioning, protection deposition, sample dicing, and focused ion beam milling of the TEM sample preparation for advanced DRAMs. The micro-structures of the devices and samples architectures were observed by using cross sectional transmission electron microscopy, scanning electron microscopy, and optical microscopy. Following these tricks can help readers to prepare TEM samples with higher quality and efficiency.

Impacts of Sample Preparation Methodology on TEM Failure Analysis of Advanced Semiconductor Devices

2011 ◽  
Author(s):  
Yongkai Zhou ◽  
Jie Zhu ◽  
Han Wei Teo ◽  
ACT Quah ◽  
Lei Zhu ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Failure Analysis ◽  
Case Studies ◽  
Thickness Measurement ◽  
Interface Roughness ◽  
Silicide Formation ◽  
Cross Sectional ◽  
Inspection Method ◽  
Low Mass

Abstract In this paper, two failure analysis case studies are presented to demonstrate the importance of sample preparation procedures to successful failure analyses. Case study 1 establishes that Palladium (Pd) cannot be used as pre-FIB coating for SiO2 thickness measurement due to the spontaneously Pd silicide formation at the SiO2/Si interface. Platinum (Pt) is thus recommended, in spite of the Pt/SiO2 interface roughness, as the pre-FIB coating in this application. In the second case study, the dual-directional TEM inspection method is applied to characterize the profile of the “invisible” tungsten residue defect. The tungsten residue appears invisible in the planeview specimen due to the low mass-thickness contrast. It is then revealed in the cross-sectional TEM inspection.

A New Method of Wafer Level Plan View TEM Sample Preparation by DualBeam

2008 ◽  
Author(s):  
Hyoung H. Kang ◽  
Michael A. Gribelyuk ◽  
Oliver D. Patterson ◽  
Steven B. Herschbein ◽  
Corey Senowitz
Keyword(s):  
Sample Preparation ◽  
Ex Situ ◽  
Wafer Level ◽  
Cross Sectional ◽  
Plan View ◽  
Manufacturing Line ◽  
Transmission Electron ◽  
Thin Lamella ◽  
Preparation Techniques

Abstract Cross-sectional style transmission electron microscopy (TEM) sample preparation techniques by DualBeam (SEM/FIB) systems are widely used in both laboratory and manufacturing lines with either in-situ or ex-situ lift out methods. By contrast, however, the plan view TEM sample has only been prepared in the laboratory environment, and only after breaking the wafer. This paper introduces a novel methodology for in-line, plan view TEM sample preparation at the 300mm wafer level that does not require breaking the wafer. It also presents the benefit of the technique on electrically short defects. The methodology of thin lamella TEM sample preparation for plan view work in two different tool configurations is also presented. The detailed procedure of thin lamella sample preparation is also described. In-line, full wafer plan view (S)TEM provides a quick turn around solution for defect analysis in the manufacturing line.

scholarly journals Patients perspectives on drug shortages in six European hospital settings – a cross sectional study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Darija Kuruc Poje ◽  
Domagoj Kifer ◽  
Isabelle Huys ◽  
Joao Miranda ◽  
Helena Jenzer ◽  
...  
Keyword(s):  
Management Practices ◽  
Healthcare Professionals ◽  
Demographic Data ◽  
General Information ◽  
Basic Knowledge ◽  
Drug Shortage ◽  
Cross Sectional ◽  
Drug Shortages ◽  
Good Communication ◽  
Information Preferences

Abstract Background It is known that drug shortages represent a major challenge for all stakeholders involved in the process, but there is little evidence regarding insights into patients′ awareness and perspectives. This study aimed to investigate the patients-perceived drug shortages experience and their view on outcomes in different European hospital settings. Furthermore, we wanted to explore information preferences on drug shortages. Methods A retrospective, cross sectional, a mixed method study was conducted in six European hospital settings. One hospital (H) from each of this country agreed to participate: Bosnia and Herzegovina (H-BiH), Croatia (H-CR), Germany (H-GE), Greece (H-GR), Serbia (H-SE) and Poland (H-PO). Recruitment and data collection was conducted over 27 months from November 2017 until January 2020. Overall, we surveyed 607 patients which completed paper-based questionnaire. Questions related to: general information (demographic data), basic knowledge on drug shortages, drug shortages experienced during hospitalization and information preferences on drug shortage. Differences between hospital settings were analyzed using Chi-squared test or Fisher’s exact test. For more complex contingency tables, Monte Carlo simulations (N = 2000) were applied for Fisher’s test. Post-hoc hospital-wise analyses were performed using Fisher’s exact tests. False discovery rate was controlled using the Bonferroni method. Analyses were performed using R: a language and environment for statistical computing (v 3.6.3). Results 6 % of patients reported experiences with drug shortages while hospitalized which led to a deterioration of their health. The majority of affected patients were hospitalized at hematology and/or oncology wards in H-BiH, H-PO and H-GE. H-BiH had the highest number of affected patients (18.1 %, N = 19/105, p < 0.001) while the fewest patients were in H-SE (1 %, N = 1/100, p = 0.001). In addition, 82.5 %, (N = 501/607) of respondents wanted to be informed of alternative treatment options if there was a drug shortage without a generic substitute available. Majority of these patients (66.4 %, N = 386/501) prefer to be informed by a healthcare professional. Conclusions Although drug shortages led to serious medical consequences, our findings show that most of the patients did not perceive shortages as a problem. One possible interpretation is that good hospital management practices by healthcare professionals helped to mitigate the perceived impact of shortages. Our study highlights the importance of a good communication especially between patients and healthcare professionals in whom our patients have the greatest trust.

scholarly journals Quantifying asymmetry of anterior cerebral arteries as a predictor of anterior communicating artery complex aneurysm

2020 ◽  
Vol 2 (1) ◽  
pp. e000059
Author(s):  
Arjun Burlakoti ◽  
Jaliya Kumaratilake ◽  
David J Taylor ◽  
Maciej Henneberg
Keyword(s):  
Significant Contribution ◽  
Anterior Cerebral Artery ◽  
Cerebral Arteries ◽  
South Australia ◽  
General Information ◽  
Anterior Communicating Artery ◽  
Cross Sectional ◽  
Complex Aneurysm ◽  
Measured Position ◽  
Cerebral Computed Tomography

ObjectivesThe aim of this study was to establish an anatomical index for early prediction of the risk of development of aneurysms in anterior communicating arterial complex (AcomAC). The asymmetric diameter of one anterior cerebral artery (ACA) to other could alter haemodynamics and may contribute to formation of aneurysms in AcomAC and be a reliable predictor of the risk of development of aneurysms.Design and settingThis is a retrospective, observational and quantitative study, which used cerebral computed tomography angiography (CCTA) scans in South Australia.ParticipantsCCTA scans of 166 adult patients of both sexes were studied.Main outcome measuresThe internal diameters of the proximal segments of ACAs (A1s) were measured. Position and presence or absence of aneurysms in AcomAC were determined. The ratio of A1 diameters was taken as a measure of A1 asymmetry.ResultsThe ratio of diameters of A1s correlated with the occurrence of AcomAC aneurysms. The risk of development of aneurysms in AcomAC was much greater (80%, OR=47.3) when one A1 segment’s radius was at least 50% larger (ie, 2.25 times cross-sectional area) than the other.ConclusionThe general information on asymmetric A1 has been published previously. The present findings have significant contribution since the A1s asymmetry ratios have been categorised in ascending order and matched with the presence of AcomAC aneurysms. The asymmetry ratio of the A1 is a good predictor for the development of AcomAC aneurysms. Reconstruction of the asymmetric A1 could be done if the technology gets advanced.

scholarly journals The Growth of Semiconductor Thin Films Studied by RHEED

1990 ◽  
Vol 43 (5) ◽  
pp. 583
Author(s):  
GL Price
Keyword(s):  
Thin Films ◽  
Surface Science ◽  
High Vacuum ◽  
High Energy ◽  
Ultra High Vacuum ◽  
Large Area ◽  
Growth Modes ◽  
Semiconductor Thin Films ◽  
Wide Range ◽  
Recent Developments

Recent developments in the growth of semiconductor thin films are reviewed. The emphasis is on growth by molecular beam epitaxy (MBE). Results obtained by reflection high energy electron diffraction (RHEED) are employed to describe the different kinds of growth processes and the types of materials which can be constructed. MBE is routinely capable of heterostructure growth to atomic precision with a wide range of materials including III-V, IV, II-VI semiconductors, metals, ceramics such as high Tc materials and organics. As the growth proceeds in ultra high vacuum, MBE can take advantage of surface science techniques such as Auger, RHEED and SIMS. RHEED is the essential in-situ probe since the final crystal quality is strongly dependent on the surface reconstruction during growth. RHEED can also be used to calibrate the growth rate, monitor growth kinetics, and distinguish between various growth modes. A major new area is lattice mismatched growth where attempts are being made to construct heterostructures between materials of different lattice constants such as GaAs on Si. Also described are the new techniques of migration enhanced epitaxy and tilted superlattice growth. Finally some comments are given On the means of preparing large area, thin samples for analysis by other techniques from MBE grown films using capping, etching and liftoff.

scholarly journals A Survey on How Ocular Surface Demodex Infestation Interactively Associates with Diabetes Mellitus and Dry Eye Disease

2021 ◽  
Author(s):  
Chang Huang ◽  
Shuze Chen ◽  
Sheng Fu ◽  
Yingli Li ◽  
Zhenhao Li ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Dry Eye ◽  
Ocular Surface ◽  
Cross Sectional Study ◽  
General Information ◽  
Potential Interaction ◽  
Dry Eye Disease ◽  
Eye Disease ◽  
Cross Sectional ◽  
Demodex Infestation

Abstract Purpose Prevention of ocular surface (OS) Demodex infestation plays an important role in OS hygiene and variety of factors may be associated with it, in which diabetes mellitus (DM) or dry eye disease (DED) has caught the attention of most scholars. However, there has been no research on whether there was a potential interaction between DM and DED in the process of OS Demodex infestation. This cross-sectional study was implemented in Zhujiang Hospital of Southern Medical University. Methods Ophthalmologic interviews, questionnaires, and examinations were conducted. Factors including general information, DM status, dry eye condition, etc. were collected to study the correlation of DM and DED on OS Demodex infestation. Results After statistical analysis, we found that both DM (P < 0.001) and DED (P = 0.013 < 0.05) are closely associated with OS Demodex infestation. Compared with DED, DM has higher priority association with OS Demodex infestation, and patients with both diseases have a significant higher risk of OS Demodex infestation (R = 0.197, P < 0.001). Meanwhile, age (R = 0.299, P < 0.001) and hypertension (P < 0.05) were also correlated with OS Demodex infestation. Conclusion This study provides a new evidence-based basis for clinical prevention and management of OS Demodex infestation.

scholarly journals Knowledge of breast cancer among medical students in Syrian Private University, Syria: a cross-sectional study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Hlma Ismail ◽  
Mosa Shibani ◽  
Hanaa Wael Zahrawi ◽  
Ali Fouad Slitin ◽  
Mhd Amin Alzabibi ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Risk Factors ◽  
Medical Students ◽  
Clinical Features ◽  
Smoking Status ◽  
Private University ◽  
Cross Sectional Study ◽  
General Information ◽  
Sectional Study ◽  
Cross Sectional

Abstract Background Breast cancer is the most common cancer among women and the second leading cause of cancer death globally. Since early diagnosis is crucial to reducing mortality, high levels of knowledge regarding general information, risk factors, and symptoms are required among healthcare professionals to deliver breast cancer care. This study aimed to determine Syrian medical students’ knowledge about breast cancer in the fields of general knowledge, common clinical features, and risk factors. Methods This cross-sectional study was conducted at the Syrian Private University in October 2019 (Breast Cancer Awareness Month), Damascus, during the Syrian war crisis. Data were collected through self-administered surveys and analyzed using the Statistical Package for Social Sciences version 25.0 (SPSS Inc., United States). The chi-square test was applied to assess the relationship between the level of knowledge and gender. One way analysis of variance was performed to assess the overall differences in mean knowledge score by study year, GPA, mother’s education, and source of information. Unpaired Student’s T-test was used to analyze the differences in mean knowledge scores (continuous variable) based on smoking status and alcohol consumption. Results Of 320 students, 301 completed the questionnaire (response rate = 94.0%), of which 179(59.5%) were males. The study revealed above-average knowledge scores (total mean = 68.4%) regarding breast cancer, general information (71.9%), common clinical features (71.6%), and risk factors (71.6%). Clinical students (4th, 5th, and 6th years) scored higher compared with pre-clinical students (1st, 2nd, and 3rd years). Conclusion This study showed above-average knowledge scores regarding breast cancer. More efforts to correct misinformation, through reassessing the university curriculum and promoting awareness about breast cancer are required.

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