Study on the P-Type Doping of AlGaN/GaN Superlattice for Blue LED

2011 ◽  
Vol 343-344 ◽  
pp. 97-100
Author(s):  
Jun Feng Chen
Keyword(s):  
Active Layer ◽  
Ohmic Contact ◽  
Annealing Temperature ◽  
Period Length ◽  
Blue Led ◽  
Al Content ◽  
Superlattice Structure ◽  
P Type ◽  
Relationship Of ◽  
The Relationship

We studied the relationship of the superlattice structure with the doping efficiency in detail by semi-classic calculation and follow experiment. The results show that period length of about 9nm and Al content of 30% is optimal. The Hall, AFM and PL measurement show that the best annealing temperature under atmosphere is about 540°C to 580°C. Finally we obtained the sample with resistivity of 0.31Ω·cm. It can be used for fabricating p type ohmic contact and active layer for blue LED.

Growth and Measurement of Mg Doped AlGaN/GaN Superlattice with Low Resistiviy

2012 ◽  
Vol 549 ◽  
pp. 274-277
Author(s):  
Jun Feng Chen
Keyword(s):  
Al Content ◽  
Superlattice Structure ◽  
Annealing Conditions ◽  
Great Progress ◽  
Bulk Gan ◽  
P Type ◽  
Relationship Of ◽  
The Relationship ◽  
Mg Doped

Although the research of bulk GaN material has take great progress in recent years, while the high quality of p-type GaN material still is an obstacle to fabricate the HBT and LD devices. In this paper we growth a group of Mg doped AlGaN/GaN superlattices under variant conditions. The Hall, AFM, PL and HR-XRD measurement are taken to find the relationship of sample quality with the superlattice structure, growth and annealing conditions. The results show that the period length of about 9nm and Al content of 30% is the optimal structure; the best annealing temperature under tmosphere is about 540°C to 580°C. At last the p-type AlGaN/GaN superlattice with resistivity of 0.31Ω•cm is fabricated which can be utilize for the contact layers of blue LEDs.

An Algorithm of Iterative Learning Control Based on Vector Plots Analysis and its Robustness

2012 ◽  
Vol 557-559 ◽  
pp. 2065-2069
Author(s):  
Chang Liang Liu ◽  
Wan Gen Jia
Keyword(s):  
Iterative Learning Control ◽  
Control Algorithm ◽  
Learning Control ◽  
Iterative Learning ◽  
Slow Convergence ◽  
Angle Correction ◽  
Convergence Process ◽  
P Type ◽  
Relationship Of ◽  
The Relationship

Abstract: In order to solve the problem of slow convergence, an iterative learning control algorithm based on vector plots analysis is proposed. By introducing the geometric principle, that angle and side length of corresponding relationship in the same triangle, and transforming output’s error relationship into the relationship of the angel, the P-type is rewarded or penalized. The new algorithm with angle-correction speeds up significantly the convergence process. For illustration, a numerical simulation is utilized to show its efficiency and superiority. Empirical results show that the new algorithm is faster than P-type to make the system convergence .The method modifying P-type by angle is entirely feasible. The system’s output converges to the desired trajectory. The new algorithm can effectively solve the slow convergence problem. Introduction

The Experimental Research of Air Explosion of Non-Ideal Explosives

2015 ◽  
Vol 723 ◽  
pp. 266-270
Author(s):  
Jian Yu Chen ◽  
Geng Guang Xu
Keyword(s):  
Shock Wave ◽  
Experimental Research ◽  
High Energy ◽  
Human Being ◽  
Damage Area ◽  
Al Content ◽  
Air Explosion ◽  
Relationship Of ◽  
The Relationship

The relationship of shock wave peak overpressure and the positive impulse of 10kg TNT, PW0,PW20,PW30 high energy explosives with different Al content and distance were studied through air explosion experiments. Besides, the damage of 140kg explosives to concrete and human being were analysized and calculated based on the fitted formulas, which shows that the damage area of PW20 is larger than other explosives.

Growth Study of p-Type 4H-SiC with Using Aluminum and Nitrogen Co-Doping by 2-Zone Heating Sublimation Method

2015 ◽  
Vol 821-823 ◽  
pp. 47-50 ◽  
Author(s):  
Kazuma Eto ◽  
Tomohisa Kato ◽  
Satoru Takagi ◽  
Tomonori Miura ◽  
Yasushi Urakami ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Growth Study ◽  
Co Doping ◽  
Sublimation Method ◽  
P Type ◽  
Relationship Of ◽  
The Relationship

p-type SiC crystals doped with aluminum and nitrogen were grown by the sublimation method. We found that Al and N co-doping is effective for stabilized growth of p-type 4H-SiC polytype. We studied the relationship of polytype of grown crystals and the condition of Al and N feeding during the crystal growth. p-type 4H-SiC withp~1 x 1018cm-3are stably-obtained with this method.

Annealing Study of Ga Implanted p-Type 6H-SiC for Ohmic Contact Metallizations

2000 ◽  
Vol 640 ◽  
Author(s):  
M. Prenatt ◽  
A. A. Iliadis ◽  
R. D. Vispute ◽  
M. C. Wood ◽  
M. Derenge ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Contact Resistance ◽  
Ohmic Contact ◽  
Annealing Temperature ◽  
Surface Damage ◽  
Capping Layer ◽  
Force Microscopy ◽  
Annealing Study ◽  
P Type ◽  
Sic Wafer

ABSTRACTShallow implantations of Ga ions were performed on p-type 6H-SiC by conventional broad area implantation, and the physical and electrical properties of the Ga-SiC system upon high temperature annealing were examined, in order to understand the role of Ga in ohmic contact formation. The shallow implantation depth (30 nm) and high Ga doses ranging between 1×1015 and 1×1016 cm−2, resulted in heavy surface damage as observed by atomic force microscopy surveys. Samples annealed using a sacrificial SiC wafer as a capping layer, showed no improvement in surface roughness for annealing up to 1300 °C, while at 1500 °C, surface roughness was markedly changed. At 1600 °C the surface re-crystallized back to the stepped terraced morphology of the un-implanted surface but with significantly larger step and terrace size. At this annealing temperature, heavy Ga loss from the surface was observed. Samples annealed at 1500 °C using an AlN capping layer, showed significant outdiffusion of Si into the AlN layer, and redistribution of Ga within the SiC surface. The contact resistance of as-implanted and annealed samples using the sacrificial SiC wafer, were measured by the TLM method. Although contact resistance was found to decrease with increasing annealing temperature, sheet resistance increased, and contact resistance values were higher than expected, indicating that the heavy loss of Ga atoms contributed to the increased levels of contact resistance.

Effect of Heat Treatment on Microstructure and Properties of Ti-6.5Al-1.5Mo-2.5V-2Zr Titanium Alloy

2013 ◽  
Vol 652-654 ◽  
pp. 1076-1079
Author(s):  
Bing Zhou ◽  
Shang Zhou Zhang
Keyword(s):  
Heat Treatment ◽  
Titanium Alloy ◽  
Phase Field ◽  
Annealing Temperature ◽  
Microstructure And Properties ◽  
Β Phase ◽  
Heat Treated ◽  
Alloy Heat ◽  
Relationship Of ◽  
The Relationship

The relationship of microstructure and properties of Ti-6.5Al-1.5Mo-2.5V-2Zr titanium alloy heat-treated in the α+β phase field was studied. It was found that globular or bimodal microstructures were obtained for alloy annealed at 400-950°C. Ductility decreased with increasing annealing temperature, while the strength showed a minimum at 800°C. The properties at the center of billet are lower than that at the edge due to the low cooling rate after forging. With the increase of test temperature, the strength decreased and ductility increased.

The relationship of the scleractinian corals to the rugose corals

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver
Keyword(s):  
Critical Points ◽  
Scleractinian Corals ◽  
Convincing Evidence ◽  
Early Triassic ◽  
Rugose Corals ◽  
History Of ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship ◽  
Biologic Factors

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Studies on Leukemogenic and Sarcomagenic Viruses

1970 ◽  
Vol 28 ◽  
pp. 156-157
Author(s):  
Leon Dmochowski
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Morphological Properties ◽  
Mode Of Development ◽  
Relationship Of ◽  
The Relationship

Electron microscopy has proved to be an invaluable discipline in studies on the relationship of viruses to the origin of leukemia, sarcoma, and other types of tumors in animals and man. The successful cell-free transmission of leukemia and sarcoma in mice, rats, hamsters, and cats, interpreted as due to a virus or viruses, was proved to be due to a virus on the basis of electron microscope studies. These studies demonstrated that all the types of neoplasia in animals of the species examined are produced by a virus of certain characteristic morphological properties similar, if not identical, in the mode of development in all types of neoplasia in animals, as shown in Fig. 1.

The relationship of IGE receptor topography to signaling activity in RBL-2H3 mast cells

1991 ◽  
Vol 49 ◽  
pp. 236-237
Author(s):  
J.R. Pfeiffer ◽  
J.C. Seagrave ◽  
C. Wofsy ◽  
J.M. Oliver
Keyword(s):  
Mast Cells ◽  
Protein A ◽  
Scattered Electron ◽  
Ige Receptor ◽  
Receptor Complexes ◽  
Ige Binding ◽  
Electron Imaging ◽  
Small Clusters ◽  
Relationship Of ◽  
The Relationship

In RBL-2H3 rat leukemic mast cells, crosslinking IgE-receptor complexes with anti-IgE antibody leads to degranulation. Receptor crosslinking also stimulates the redistribution of receptors on the cell surface, a process that can be observed by labeling the anti-IgE with 15 nm protein A-gold particles as described in Stump et al. (1989), followed by back-scattered electron imaging (BEI) in the scanning electron microscope. We report that anti-IgE binding stimulates the redistribution of IgE-receptor complexes at 37“C from a dispersed topography (singlets and doublets; S/D) to distributions dominated sequentially by short chains, small clusters and large aggregates of crosslinked receptors. These patterns can be observed (Figure 1), quantified (Figure 2) and analyzed statistically. Cells incubated with 1 μg/ml anti-IgE, a concentration that stimulates maximum net secretion, redistribute receptors as far as chains and small clusters during a 15 min incubation period. At 3 and 10 μg/ml anti-IgE, net secretion is reduced and the majority of receptors redistribute rapidly into clusters and large aggregates.

Sign in / Sign up

Export Citation Format

Share Document