Interpretation of Sudden Failures in Pump Laser Diodes

1997 ◽  
Author(s):  
A. Bonfiglió ◽  
M. Vanzi ◽  
M. B. Casu ◽  
F. Magistrali ◽  
M. Maini ◽  
...  
Keyword(s):  
Failure Modes ◽  
Optical Power ◽  
Constant Current ◽  
Recombination Site ◽  
Cross Sectional ◽  
Native Defects ◽  
Defect Growth ◽  
Pump Lasers ◽  
Defect Reaction

Abstract The occurrence of sudden failures has been reported for 980 nm SL SQW InGaAs pump lasers. The post-mortem analysis reveals failure modes that are consistent with the formation of defects at the active area. The problem calls for two separate efforts: monitoring the degradation at suitable time resolution and structural characterization of defects. This article reports about the optical power and overall voltage monitoring results during a constant current lifetest, in which "sudden failures" switched off the lasers in a few hours, after 1500 hours of regular life, and about their interpretation based on TEM cross-sectional images across an EBIC-detected high recombination site. The hypothesis that Recombination Enhanced Defect Reaction (REDR) is a suitable mechanism for defect growth in forward biased GaAs-based diodes is proposed and discussed that REDR is the origin of the observed sudden failures, starting from native defects located in "cool" regions.

Characterization of Er/O-doped Si-LEDs with Low Thermal Quenching

2005 ◽  
Vol 866 ◽  
Author(s):  
A. Karim ◽  
W.-X. Ni ◽  
A. Elfving ◽  
P.O.Å. Persson ◽  
G.V. Hansson
Keyword(s):  
Temperature Dependence ◽  
Reverse Bias ◽  
Thermal Quenching ◽  
Constant Current ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Low Energy Electrons ◽  
Higher Temperature ◽  
Electron Emitters

AbstractElectroluminescence studies of MBE-grown Er/O-doped Si-diodes at reverse bias have been done. For some devices there is much reduced thermal quenching of the emission at 1.54 νm. There are examples where the temperature dependence is abnormal in that the intensity for a constant current even increases with temperature up to e.g. 80 °C. These devices have been studied with cross-sectional transmission electron microscopy to see the microstructure of the Er/O-doped layers as well as the B-doped SiGe-layers that are used as electron emitters during reverse bias. Although there are defects in the layers there is no evidence for large thick precipitates of SiO2. While reduced thermal quenching often is attributed to having the Er-ions within SiO2 layers, this is not the case for our structures as evidenced by our TEM-studies. The origin of the abnormal temperature dependence is attributed to the two mechanisms of breakdown in the reverse-biased diodes. At low temperature the breakdown current is mainly due to avalanche resulting in low-energy electrons and holes that quenches the intensity by Auger deexcitation of the Er-ions. At higher temperature the breakdown current is mainly phonon-assisted tunneling which results in a more efficient pumping with less de-excitation of the Er-ions. Finally at the highest temperatures the thermal quenching sets in corresponding to an activation energy of 125 meV, which is slightly lower than 150 meV that has been reported in other studies.

Microstructural characterization of CoPtCr/Cr thin film disks by cross-section TEM and elongated probe micro-diffraction

1991 ◽  
Vol 49 ◽  
pp. 762-763
Author(s):  
M.A. Parker ◽  
K.E. Johnson ◽  
C. Hwang ◽  
A. Bermea
Keyword(s):  
Magnetic Recording ◽  
Electron Probe ◽  
Microstructural Characterization ◽  
Crystallographic Structure ◽  
Recording Media ◽  
Layer By Layer ◽  
Cross Sectional ◽  
New Techniques ◽  
Polished Side

We have reported the dependence of the magnetic and recording properties of CoPtCr recording media on the thickness of the Cr underlayer. It was inferred from XRD data that grain-to-grain epitaxy of the Cr with the CoPtCr was responsible for the interaction observed between these layers. However, no cross-sectional TEM (XTEM) work was performed to confirm this inference. In this paper, we report the application of new techniques for preparing XTEM specimens from actual magnetic recording disks, and for layer-by-layer micro-diffraction with an electron probe elongated parallel to the surface of the deposited structure which elucidate the effect of the crystallographic structure of the Cr on that of the CoPtCr.XTEM specimens were prepared from magnetic recording disks by modifying a technique used to prepare semiconductor specimens. After 3mm disks were prepared per the standard XTEM procedure, these disks were then lapped using a tripod polishing device. A grid with a single 1mmx2mm hole was then glued with M-bond 610 to the polished side of the disk.

TEM characterization of silicon epitaxial layer grown on Si-TaS2, eutectic composites

1991 ◽  
Vol 49 ◽  
pp. 802-803
Author(s):  
C.M. Sung ◽  
M. Levinson ◽  
M. Tabasky ◽  
K. Ostreicher ◽  
B.M. Ditchek
Keyword(s):  
Substrate Surface ◽  
Bulk Sample ◽  
Surface Cleaning ◽  
Native Oxide ◽  
Czochralski Growth ◽  
Ion Milling ◽  
Cross Sectional ◽  
Cleaning Methods ◽  
Field Emission Cathodes

Directionally solidified Si/TaSi2 eutectic composites for the development of electronic devices (e.g. photodiodes and field-emission cathodes) were made using a Czochralski growth technique. High quality epitaxial growth of silicon on the eutectic composite substrates requires a clean silicon substrate surface prior to the growth process. Hence a preepitaxial surface cleaning step is highly desirable. The purpose of this paper is to investigate the effect of surface cleaning methods on the epilayer/substrate interface and the characterization of silicon epilayers grown on Si/TaSi2 substrates by TEM.Wafers were cut normal to the <111> growth axis of the silicon matrix from an approximately 1 cm diameter Si/TaSi2 composite boule. Four pre-treatments were employed to remove native oxide and other contaminants: 1) No treatment, 2) HF only; 3) HC1 only; and 4) both HF and HCl. The cross-sectional specimens for TEM study were prepared by cutting the bulk sample into sheets perpendicular to the TaSi2 fiber axes. The material was then prepared in the usual manner to produce samples having a thickness of 10μm. The final step was ion milling in Ar+ until breakthrough occurred. The TEM samples were then analyzed at 120 keV using the Philips EM400T.

Characterization of Rh/Si multilayer structure by HREM and HAADF

1992 ◽  
Vol 50 (1) ◽  
pp. 122-123
Author(s):  
Y. Cheng ◽  
J. Liu ◽  
M.B. Stearns ◽  
D.G. Steams
Keyword(s):  
Normal Incidence ◽  
High Resolution Electron Microscopy ◽  
X Rays ◽  
Beam Direction ◽  
Cross Sectional ◽  
Optical Elements ◽  
Resolution Electron ◽  
Point To Point ◽  
Better Than

The Rh/Si multilayer (ML) thin films are promising optical elements for soft x-rays since they have a calculated normal incidence reflectivity of ∼60% at a x-ray wavelength of ∼13 nm. However, a reflectivity of only 28% has been attained to date for ML fabricated by dc magnetron sputtering. In order to determine the cause of this degraded reflectivity the microstructure of this ML was examined on cross-sectional specimens with two high-resolution electron microscopy (HREM and HAADF) techniques.Cross-sectional specimens were made from an as-prepared ML sample and from the same ML annealed at 298 °C for 1 and 100 hours. The specimens were imaged using a JEM-4000EX TEM operating at 400 kV with a point-to-point resolution of better than 0.17 nm. The specimens were viewed along Si [110] projection of the substrate, with the (001) Si surface plane parallel to the beam direction.

Comparison of Ion-Milling Techniques For Cross-Sectional TEM of Semiconductors

1985 ◽  
Vol 43 ◽  
pp. 166-167
Author(s):  
Julia T. Luck ◽  
C. W. Boggs ◽  
S. J. Pennycook
Keyword(s):  
Analytical Techniques ◽  
Sample Surface ◽  
Ion Milling ◽  
Cross Sectional ◽  
Reliable Technique ◽  
Near Surface ◽  
Transmission Electron ◽  
Thin Region ◽  
Transient Thermal

The use of cross-sectional Transmission Electron Microscopy (TEM) has become invaluable for the characterization of the near-surface regions of semiconductors following ion-implantation and/or transient thermal processing. A fast and reliable technique is required which produces a large thin region while preserving the original sample surface. New analytical techniques, particularly the direct imaging of dopant distributions, also require good thickness uniformity. Two methods of ion milling are commonly used, and are compared below. The older method involves milling with a single gun from each side in turn, whereas a newer method uses two guns to mill from both sides simultaneously.

High-resolution transmission electron microscopic study of highly oxygen doped silicon layer

1989 ◽  
Vol 47 ◽  
pp. 692-693
Author(s):  
H. Takaoka ◽  
M. Tomita ◽  
T. Hayashi
Keyword(s):  
High Resolution ◽  
Oxygen Concentration ◽  
Silicon Layer ◽  
Detailed Structure ◽  
Electron Microscopic ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Doped Silicon ◽  
Argon Ion

High resolution transmission electron microscopy (HRTEM) is the effective technique for characterization of detailed structure of semiconductor materials. Oxygen is one of the important impurities in semiconductors. Detailed structure of highly oxygen doped silicon has not clearly investigated yet. This report describes detailed structure of highly oxygen doped silicon observed by HRTEM. Both samples prepared by Molecular beam epitaxy (MBE) and ion implantation were observed to investigate effects of oxygen concentration and doping methods to the crystal structure.The observed oxygen doped samples were prepared by MBE method in oxygen environment on (111) substrates. Oxygen concentration was about 1021 atoms/cm3. Another sample was silicon of (100) orientation implanted with oxygen ions at an energy of 180 keV. Oxygen concentration of this sample was about 1020 atoms/cm3 Cross-sectional specimens of (011) orientation were prepared by argon ion thinning and were observed by TEM at an accelerating voltage of 400 kV.

Electrical Characterization of Different Failure Modes in Sub-100 nm Devices Using Nanoprobing Technique

2009 ◽  
Author(s):  
E. Hendarto ◽  
S.L. Toh ◽  
J. Sudijono ◽  
P.K. Tan ◽  
H. Tan ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Focused Ion Beam ◽  
Failure Modes ◽  
Ion Beam ◽  
Electrical Characterization ◽  
Nickel Silicide ◽  
Fault Isolation ◽  
Technology Nodes ◽  
Scanning Electron

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.

Case Study and Fault Modeling for Wrong Redundancy Evaluation on DRAM Devices

2007 ◽  
Author(s):  
Martin Versen ◽  
Dorina Diaconescu ◽  
Jerome Touzel
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Fault Modeling ◽  
Mode Analysis ◽  
Root Cause ◽  
Failure Mode Analysis

Abstract The characterization of failure modes of DRAM is often straight forward if array related hard failures with specific addresses for localization are concerned. The paper presents a case study of a bitline oriented failure mode connected to a redundancy evaluation in the DRAM periphery. The failure mode analysis and fault modeling focus both on the root-cause and on the test aspects of the problem.

Genomic, Metagenomic and Transcriptomic Characterization of the Clinical Forms of COVID-19: A Comparative Cross-Sectional Study

2020 ◽  
Author(s):  
Christophe Rodriguez ◽  
Nicolas de Prost ◽  
Slim Fourati ◽  
Claudie Lamoureux ◽  
Guillaume Gricourt ◽  
...  
Keyword(s):  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Clinical Forms

Significados de Morte: o Discurso do Sujeito Coletivo da Enfermagem / Meaning of Death: the collective subject speech of the nursing staff

1970 ◽  
Vol 6 (1) ◽  
pp. 52-58
Author(s):  
Fellipe Afonso de Azevedo ◽  
Noé D’jalma Araújo ◽  
Néliton Célio de Novais ◽  
José Vítor da Silva ◽  
Renato Augusto Passos
Keyword(s):  
Nursing Staff ◽  
Hospital Setting ◽  
Field Research ◽  
Structured Interview ◽  
Minas Gerais ◽  
Structured Interviews ◽  
Cross Sectional ◽  
Emergency Units ◽  
Methodological Guidelines

RESUMOObjetivo: o presente trabalho teve como objetivo identificar os significados de morte emergentes das equipes de enfermagem que atuam nas unidades de Pronto Socorro e Unidade de Terapia Intensiva (UTI) em uma entidade de médio porte situada no Sul de Minas Gerais. Materiais e métodos: estudo de abordagem qualitativa, do tipo descritivo, de campo e transversal. A amostra estudada foi composta de oito enfermeiros, 22 técnicos e quatro auxiliares de enfermagem, totalizando 34 profissionais, sendo utilizado o instrumento de caracterização pessoal e profissional da equipe de enfermagem e o roteiro de entrevista semiestruturada. A amostragem foi proposital. A coleta de dados foi realizada através de entrevista semiestruturada, gravada e transcrita. As diretrizes metodológicas do Discurso do Sujeito Coletivo foram utilizadas para a seleção das ideias centrais e expressões-chave correspondentes, a partir das quais foram extraídos os discursos dos sujeitos, no cenário da instituição hospitalar. Resultados e Discussão: ao analisar o tema “significados de morte”, obtiveram-se as seguintes ideias centrais: “passagem”, “diversos significados”, “fim da vida” e “fim e começo de outra vida”. Conclusão: As concepções acerca do tema morte para os profissionais participantes deste trabalho reforça a necessidade de estudos sobre o tema durante a formação acadêmica. Certos de que irão vivenciar este tipo de situação no dia-a-dia profissional, é preciso prepará-los psicologicamente para isso.Palavras-chave: Morte, Equipe de enfermagem, Assistência ao paciente.ABSTRACTObjective: This study aimed to identify the meanings of emerging death of the nursing staff working in the Emergency Units and Intensive Care Unit (ICU) in a medium-sized entity located in southern Minas Gerais. Materials and methods: A cross-sectional qualitative field research. The sample was composed of 8 nurses, 22 technicians and 4 nursing assistants, totaling 34 professionals. It was used a tool of personal and professional characterization of the nursing team and a semi-structured interview. Sampling was intentional. Data collection was conducted through semi-structured interviews, that were recorded and transcribed. The methodological guidelines of the Collective Subject Speech were used for the selection of the central ideas and corresponding key expressions, from which the speeches of the subjects were taken, in the hospital setting. Results and discussion: to examine the topic "death meanings" yielded the following core ideas: "pass", "different meanings", "end of life" and "end and beginning of another life." Conclusion: The conceptions about the death theme for the professional participants of this study reinforces the need for studies on the subject during their academic training. It is certain that they will experience this type of situation on their daily professional routine, therefore there is a need to prepare them psychologically for this.Keywords: Death, Nursing staff, Patient care.

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