Photoluminescence and Plane-View Tem Studies of Epitaxial ZnSe Layers on GaAs After H2 Gas Heat-Treatment

1989 ◽  
Vol 145 ◽  
Author(s):  
Maki Sekoguchi-pl ◽  
Takashi Murase ◽  
Tsunemasa Taguchi
Keyword(s):  
Heat Treatment ◽  
Tensile Strain ◽  
Deep Level ◽  
Annealed Film ◽  
Edge Emission ◽  
Deep Acceptor ◽  
Deviation From Stoichiometry ◽  
Microstructural Defects ◽  
Plane View ◽  
Low Temperature Photoluminescence

AbstractLow-temperature photoluminescence and plane-view TEN observations have been carried out to investigate the strain and microstructural defects in MOCVD-grown ZnSe/(100)GaAs after post- growth annealing in H2gas at temperature between 350 and 500V. A 0.35 µm thick ZnSe epitaxial layer is originally under compres- sive strain, but after annealing this receives considerably tensile strain, and the neutral deep-acceptor bound exciton () line and the edge-emission band at about 2.72 eV newly appear. The observed changes are interpreted in terms of the energy down- shift of the excitonic lines and deviation from stoichiometry. The annealed film, which deteriorated as a result of generations of dislocation tangles and small loops, results in the strong deep-level emissions around 2.25 eV.

Effect of Different Heat Treatments on Mechanical Properties of Laser Sintered Additive Manufactured Parts

2017 ◽  
Author(s):  
Sagar Sarkar ◽  
Cheruvu Siva Kumar ◽  
Ashish Kumar Nath
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Yield Strength ◽  
Tensile Strain ◽  
Wear Loss ◽  
Layer By Layer ◽  
Solution Annealing ◽  
Wear Properties ◽  
Sem Images ◽  
Wide Range

One of the most popular additive manufacturing processes is laser based direct metal laser sintering process which enables us to make complex three dimensional parts directly from CAD models. Due to layer by layer formation, parts built in this process tend to be anisotropic in nature. Suitable heat treatment can reduce this anisotropic behaviour by changing the microstructure. Depending upon the applications, a wide range of mechanical properties can be achieved between 482–621° C temperature for precipitation-hardened stainless steels. In the present study effect of different heat treatment processes, namely solution annealing, ageing and overaging, on tensile strength, hardness and wear properties has been studied in detail. Suitable metallurgical and mechanical characterization techniques have been applied wherever required, to support the experimental observations. Results show H900 condition gives highest yield strength and lowest tensile strain at break whereas solution annealing gives lowest yield strength and as-built condition gives highest tensile strain at break. SEM images show that H900 and H1150 condition produces brittle and ductile morphology respectively which in turn gives highest and lowest hardness value respectively.XRD analysis shows presence of austenite phases which can increase hardness at the cost of ductility. Average wear loss for H900 condition is highest whereas it is lowest for solution annealed condition. Further optical and SEM images have been taken to understand the basic wear mechanism involved.

Defect Spectroscopy on Damp-Heat Treated ZnO/CdS/Cu(In,Ga)(S,Se)2/Mo Heterojunction Solar Cells

2003 ◽  
Vol 58 (12) ◽  
pp. 691-702 ◽  
Author(s):  
C. Deibel ◽  
V. Dyakonov ◽  
J. Parisi
Keyword(s):  
Heat Treatment ◽  
Activation Energy ◽  
Solar Cells ◽  
Deep Level ◽  
Heat Exposure ◽  
Continuous Distribution ◽  
Open Circuit ◽  
Defect States ◽  
Band Bending ◽  
Test Cells

The changes of defect characteristics induced by accelerated lifetime tests on solar cells of the heterostructure ZnO/CdS/Cu(In,Ga)(S,Se)2/Mo are investigated. Encapsulated modules were shown to be stable against water vapor and oxygen under outdoor conditions, whereas the fill factor and open-circuit voltage of non-encapsulated test cells are reduced after prolonged damp heat treatment in the laboratory, leading to a reduced energy conversion efficiency. We subjected non-encapsulated test cells to extended damp heat exposure at 85 ◦C ambient temperature and 85% relative humidity for various time periods (6 h, 24 h, 144 h, 294 h, and 438 h). In order to understand the origin of the pronounced changes of the cells, we applied temperature-dependent current-voltage and capacitance voltage measurements, admittance spectroscopy, and deep-level transient spectroscopy. We observed the presence of electronic defect states which show an increasing activation energy due to damp heat exposure. The corresponding attempt-to-escape frequency and activation energy of these defect states obey the Meyer-Neldel relation. We conclude that the response originates from an energetically continuous distribution of defect states in the vicinity of the CdS/chalcopyrite interface. The increase in activation energy indicates a reduced band bending at the Cu(In,Ga)(S,Se)2 surface.We also observed changes in the bulk defect spectra due to the damp-heat treatment. - PACS: 73.20.hb, 73.61.Le

scholarly journals PL Study on the Effect of Cu on the Front Side Luminescence of CdTe/CdS Solar Cells

Coatings ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 435 ◽  
Author(s):  
Halina Opyrchal ◽  
Dongguo Chen ◽  
Zimeng Cheng ◽  
Ken Chin
Keyword(s):  
Heat Treatment ◽  
Energy Gap ◽  
Cdte Layer ◽  
Large Shift ◽  
Additional Band ◽  
Junction Area ◽  
Solid Film ◽  
Cdcl2 Treatment ◽  
Neutral Acceptor ◽  
Low Temperature Photoluminescence

The effect of Cu on highly efficient CdTe thin solid film cells with a glass/TCO/CdS/CdTe structure subjected to CdCl2 treatment was investigated by low-temperature photoluminescence (PL). The PL of the CdS/CdTe junction in samples without Cu deposition revealed a large shift in the bound exciton position due to the formation of CdSxTe1−x alloys with Eg (alloy) ≅ 1.557 eV at the interface region. After Cu deposition on the CdTe layer and subsequent heat treatment, a neutral acceptor-bound exciton (A0Cu,X) line at 1.59 eV and two additional band-edge peaks at 1.54 and 1.56 eV were observed, indicating an increase in the energy gap value in the vicinity of the CdTe/CdS interface to that characteristic of bulk CdTe. These results may suggest the disappearance of the intermixing phase at the CdTe/CdS interface due to the presence of Cu atoms in the junction area and the interaction of the Cu with sulfur atoms. Furthermore, an increase in the intensity of CdS-related peaks in Cu-doped samples was observed, implying that Cu atoms were incorporated into CdS after heat treatment.

Electrical Properties and Defect States of Laser Crystallized Polycrystalline Silicon Films

2001 ◽  
Vol 664 ◽  
Author(s):  
Tadashi Watanabe ◽  
Nobuyuki Andoh ◽  
Toshiyuki Sameshima
Keyword(s):  
Heat Treatment ◽  
Electrical Conductivity ◽  
Electrical Properties ◽  
Deep Level ◽  
Silicon Films ◽  
Laser Shot ◽  
Defect States ◽  
Shot Number ◽  
Polycrystalline Silicon Films ◽  
Effective Carrier

ABSTRACTIn this paper, changes in electrical properties of laser crystallized silicon films doped with 8.5×1017-cm−3-phosphorus atoms as a function of laser shot number are investigated. The samples are treated with plasma hydrogenation for 30 sec at 130 Pa at 250 °C and additional H2O vapor heat treatment at 260 °C for 3 hours with 1.3 MPa. The electrical conductivity at room temperature become about 10−6∼10−-5 S/cm as laser shot number increases from 1 to 100. After hydrogenation and additional H2O vapor heat treatment, electrical conductivity remarkably increases to 100∼101S/cm. At laser irradiation of 20 or 50 shots after both treatments, the density of defect at deep level states and tail states are determined 1.15×1017 cm−3 and 5.7×1017cm−3 using an analysis program. Potential barrier height at grain boundary is 0.048 eV. The effective carrier density and carrier mobility are markedly increased up to1017cm−3 and 209 cm2/Vs by hydrogenation and additional H2O vapor heat treatment.

Deep-level transient spectroscopy studies of thermal donor annihilation in silicon by rapid thermal annealing

1989 ◽  
Vol 4 (2) ◽  
pp. 241-243 ◽  
Author(s):  
Yutaka Tokuda ◽  
Nobuji Kobayashi ◽  
Yajiro Inoue ◽  
Akira Usami ◽  
Makoto Imura
Keyword(s):  
Heat Treatment ◽  
Thermal Stress ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Electron Trap ◽  
Thermal Donor ◽  
Transient Spectroscopy ◽  
Spectroscopy Studies

The annihilation of thermal donors in silicon by rapid thermal annealing (RTA) has been studied with deep-level transient spectroscopy. The electron trap AO (Ec – 0.13 eV) observed after heat treatment at 450 °C for 10 h, which is identified with the thermal donor, disappears by RTA at 800 °C for 10 s. However, four electron traps, A1 (Ec 0.18 eV), A2 (Ec – 0.25 eV), A3 (Ec – 0.36 eV), and A4 (Ec – 0.52 eV), with the concentration of ∼1012 cm−3 are produced after annihilation of thermal donors by RTA. These traps are also observed in silicon which receives only RTA at 800 °C. This indicates that traps A1–A4 are thermal stress induced or quenched-in defects by RTA, not secondary defects resulting from annealing of thermal donors.

Optical Characterization of Bulk GaN Grown from a Na/Ga Flux

2002 ◽  
Vol 743 ◽  
Author(s):  
K. Palle ◽  
L. Chen ◽  
H. X. Liu ◽  
B. J. Skromme ◽  
H. Yamane ◽  
...  
Keyword(s):  
Large Scale ◽  
Deep Level ◽  
Optical Characterization ◽  
Flux Method ◽  
Triplet Structure ◽  
Bulk Gan ◽  
Scale Reactor ◽  
Low Temperature Photoluminescence ◽  
Residual Zn

ABSTRACTBulk GaN crystals up to several mm in size, grown by a Na/Ga flux method, have been characterized using room and low temperature photoluminescence (PL) and panchromatic cathodoluminescence (CL) imaging. Highly resolved excitonic PL spectra are obtained for material grown in a new, large-scale reactor. The crystal polarity affects the incorporation of residual Zn and Mg or Si acceptors and the deep level luminescence bands in c-oriented platelets. A Zn (A°,X) triplet structure with unusual thermalization properties and a highly resolved structural defect related PL peak are observed. Striations are found in some of the smaller platelets by CL imaging, but are absent in the prismatic crystals.

Influence of n-Type Doping Levels on Carrier Lifetime in 4H-SiC Epitaxial Layers

2017 ◽  
Vol 897 ◽  
pp. 238-241 ◽  
Author(s):  
Louise Lilja ◽  
Ildiko Farkas ◽  
Ian Booker ◽  
Jawad ul Hassan ◽  
Erik Janzén ◽  
...  
Keyword(s):  
Low Temperature ◽  
Deep Level Transient Spectroscopy ◽  
Doping Level ◽  
Carrier Lifetime ◽  
Deep Level ◽  
Growth Conditions ◽  
Epitaxial Layers ◽  
Drastic Decrease ◽  
Transient Spectroscopy ◽  
Low Temperature Photoluminescence

In this study we have grown thick 4H-SiC epitaxial layers with different n-type doping levels in the range 1E15 cm-3 to mid 1E18 cm-3, in order to investigate the influence on carrier lifetime. The epilayers were grown with identical growth conditions except the doping level on comparable substrates, in order to minimize the influence of other parameters than the n-type doping level. We have found a drastic decrease in carrier lifetime with increasing n-type doping level. Epilayers were further characterized with low temperature photoluminescence and deep level transient spectroscopy.

Effect of Different Heat Treatments on Mechanical Properties of Laser Sintered Additive Manufactured Parts

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Sagar Sarkar ◽  
Cheruvu Siva Kumar ◽  
Ashish Kumar Nath
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Yield Strength ◽  
Computer Aided Design ◽  
Tensile Strain ◽  
Wear Loss ◽  
Layer By Layer ◽  
Solution Annealing ◽  
Sem Images ◽  
Wide Range

One of the most popular additive manufacturing processes is laser-based direct metal laser sintering (DMLS) process, which enables us to make complex three-dimensional (3D) parts directly from computer-aided design models. Due to layer-by-layer formation, parts built in this process tend to be anisotropic in nature. Suitable heat treatment can reduce this anisotropic behavior by changing the microstructure. Depending upon the applications, a wide range of mechanical properties can be achieved between 482 °C and 621 °C temperature for precipitation-hardened stainless steels. In the present study, effect of different heat treatment processes, namely solution annealing, aging, and overaging, on tensile strength, hardness, and wear properties has been studied in detail. Suitable metallurgical and mechanical characterization techniques have been applied wherever required, to support the experimental observations. Results show H900 condition gives highest yield strength and lowest tensile strain at break, whereas solution annealing gives lowest yield strength and as-built condition gives highest tensile strain at break. Scanning electron microscope (SEM) images show that H900 and H1150 condition produces brittle and ductile morphology, respectively, which in turn gives highest and lowest hardness value, respectively. X-ray diffraction (XRD) analysis shows presence of austenite phases, which can increase ductility at the cost of hardness. Average wear loss for H900 condition is highest, whereas it is lowest for solution annealed condition. Further optical and SEM images have been taken to understand the basic wear mechanism involved.

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