scholarly journals Mobility Limitations due to Dislocations and Interface Roughness in AlGaN/AlN/GaN Heterostructure

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Qun Li ◽  
Jingwen Zhang ◽  
Li Meng ◽  
Jing Chong ◽  
Xun Hou
Keyword(s):  
Surface Roughness ◽  
Theoretical Model ◽  
Interface Roughness ◽  
Mobility Limitations ◽  
Gaussian Form ◽  
Quantitative Measurements ◽  
Transmission Electron ◽  
Dimensional Electron Gas ◽  
Exponential Correlation Function ◽  
Gan Heterostructure

The dislocations and surface roughness in an AlGaN/AlN/GaN heterostructure were analyzed by transmission electron microscopy (TEM) and atomic force microscopy (AFM), respectively, and the mobility limitation mechanisms in the two-dimensional electron gas (2DEG) were studied using a theoretical model that took into account the most important scattering mechanisms. An exponential correlation function provides a better description of the statistical properties of surface roughness than the Gaussian form and thus is adopted in the theoretical model. The calculated results are in good agreement with Hall data. The quantitative measurements of dislocations and surface roughness allow the evaluation of the relative importance of each extrinsic scattering mechanism.

Experimental investigation and modelling of light scattering in a-Si:H solar cells deposited on glass/ZnO:Al substrates

2002 ◽  
Vol 715 ◽  
Author(s):  
J. Krc ◽  
M. Zeman ◽  
O. Kluth ◽  
F. Smole ◽  
M. Topic
Keyword(s):  
Surface Roughness ◽  
Experimental Investigation ◽  
Solar Cells ◽  
Angular Distribution ◽  
Light Scattering ◽  
Optical Model ◽  
Distribution Functions ◽  
Interface Roughness ◽  
Scattering Parameters ◽  
Good Agreement

AbstractThe descriptive scattering parameters, haze and angular distribution functions of textured ZnO:Al transparent conductive oxides with different surface roughness are measured. An approach to determine the scattering parameters of all internal interfaces in p-i-n a-Si:H solar cells deposited on the glass/ZnO:Al substrates is presented. Using the determined scattering parameters as the input parameters of the optical model, a good agreement between the measured and simulated quantum efficiencies of the p-i-n a-Si:H solar cells with different interface roughness is achieved.

Post Oxidation Anneal and Re-Oxidation Effects in 5 nm SiO2 Films

1986 ◽  
Vol 76 ◽  
Author(s):  
L. Dori ◽  
M. Arienzo ◽  
Y. C. Sun ◽  
T. N. Nguyen ◽  
J. Wetzel
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Silicon Dioxide ◽  
Oxygen Vacancies ◽  
Interface Roughness ◽  
Cross Sectional ◽  
Oxide Charge ◽  
Transmission Electron ◽  
Redistribution Of Hydrogen ◽  
Transmission Electron Microscopy Cross

ABSTRACTUltrathin silicon dioxide films, 5 nm thick, were grown in a double-walled furnace at 850°C in dry O2. A consistent improvement in the electrical properties is observed following the oxidation either with a Post-Oxidation Anneal (POA) at 1000°C in N2 or with the same POA followed by a short re-oxidation (Re-Ox) step in which 1 nm of additional oxide was grown. We attribute these results to the redistribution of hydrogen and water related groups as well as to a change in the concentration of sub-oxide charge states at the Si-SiO2 interface. A further improvement observed after the short re-oxidation step had been attributed to the filling of the oxygen vacancies produced during the POA. High resolution Transmission Electron Microscopy cross-sectional observations of the Si-iSO2 interface have evidenced an increase in the interface roughness after the thermal treatment at high temperature. These results are in agreement with recent XPS data.

Electroreflectance of the AlGaN/GaN heterostructure and two-dimensional electron gas

2002 ◽  
Vol 80 (24) ◽  
pp. 4549-4551 ◽  
Author(s):  
S. R. Kurtz ◽  
A. A. Allerman ◽  
D. D. Koleske ◽  
G. M. Peake
Keyword(s):  
Electron Gas ◽  
Two Dimensional ◽  
Dimensional Electron ◽  
Two Dimensional Electron Gas ◽  
Dimensional Electron Gas ◽  
Gan Heterostructure

Interfacial Versus Cohesive Failure on Polymer-Metal Interfaces in Electronic Packaging—Effects of Interface Roughness

2002 ◽  
Vol 124 (2) ◽  
pp. 127-134 ◽  
Author(s):  
Qizhou Yao ◽  
Jianmin Qu
Keyword(s):  
Surface Roughness ◽  
Fracture Mechanics ◽  
Electronic Packaging ◽  
Interfacial Adhesion ◽  
Interfacial Strength ◽  
Interface Roughness ◽  
Cohesive Failure ◽  
Mechanics Model ◽  
Polymer Metal ◽  
Metal Interfaces

Debonding of polymer-metal interfaces often involves both interfacial and cohesive failure. Since the cohesive strength of polymers is usually much greater than the polymer-metal interfacial strength, cohesive failure near the interface is usually desired for enhancing the interfacial adhesion. Roughened surfaces generally produce more cohesive failure; therefore, they are used commonly in practice to obtain better adhesion. This paper develops a fracture mechanics model that can be used to quantitatively predict the amount of cohesive failure once the surface roughness data are given. An epoxy/Al interface was investigated using this fracture mechanics model. The predicted amount of cohesive failure as a function of surface roughness compares very well with the experimentally measured values. It is believed that this model can be extended to other polymer–metal interfaces. Contributed by the Electronic and Photonic Packaging Division for publication in the JOURNAL OF ELECTRONIC PACKAGING. Manuscript received by the EPPD.

AlxGa1-xN-Based Materials and Heterostructures

1996 ◽  
Vol 449 ◽  
Author(s):  
P. Kung ◽  
A. Saxler ◽  
D. Walker ◽  
X. Zhang ◽  
R. Lavado ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Bragg Reflectors ◽  
X Ray Diffraction ◽  
Chemical Vapor Deposition Growth ◽  
X Ray ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
Dimensional Electron Gas ◽  
P Type

ABSTRACTWe present the metalorganic chemical vapor deposition growth, n-type and p-type doping and characterization of AlxGa1-xN alloys on sapphire substrates. We report the fabrication of Bragg reflectors and the demonstration of two dimensional electron gas structures using AlxGa1-xN high quality films. We report the structural characterization of the AlxGa1-xN / GaN multilayer structures and superlattices through X-ray diffraction and transmission electron microscopy. A density of screw and mixed threading dislocations as low as 107 cm-2 was estimated in AlxGa1-xN / GaN structures. The realization of AlxGa1-xN based UV photodetectors with tailored cut-off wavelengths from 365 to 200 nm are presented.

Nanotwinned Surface on a Ternary Titanium Alloy with Increased Hardness Induced under Nanoindentations

2016 ◽  
Vol 874 ◽  
pp. 323-327
Author(s):  
Hong Xiu Zhou ◽  
Ming Lei Li ◽  
Neng Dong Duan ◽  
Bo Wang ◽  
Zhi Feng Shi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Surface Roughness ◽  
Titanium Alloy ◽  
Chemical Mechanical Polishing ◽  
Material Removal ◽  
Room Temperature ◽  
Chemical Reagents ◽  
Transmission Electron ◽  
High Temperature High Pressure

A nanotwinned surface is formed on a titanium alloy under nanoindentations. Prior to nanoindentation, blocks of a ternary titanium alloy are machined by chemical mechanical polishing. The surface roughness Ra and peak-to-valley values are 1.135 nm and 8.82 nm, respectively. The hardness in the indented surface is greatly increased, indicated from the load-displacement curves compared to the polished surfaces. Nanotwins are confirmed using transmission electron microscopy. The nanotwinned surface is uniformly generated by nanoindentations at room temperature, which is different from previous findings, in which high temperature, high pressure, or chemical reagents are usually used. The nanotwinned surface is produced by pure mechanical stress, neither material removal nor addition.

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