Effect of GaN Surface Treatment on the Morphological and Optoelectronic Response of Violet Light Emitting Diodes

2004 ◽  
Vol 831 ◽  
Author(s):  
Muhammad Jamil ◽  
James R. Grandusky ◽  
Fatemeh Shahedipour-Sandvik
Keyword(s):  
Organic Solvents ◽  
Light Emitting Diode ◽  
Photoemission Spectroscopy ◽  
Light Emitting ◽  
X Ray ◽  
Force Microscopy ◽  
Treatment Processes ◽  
Atomic Force ◽  
Short Period ◽  
High Roughness

ABSTRACTWe report on the study of the effect of various surface chemical treatment processes of n-GaN template layers used for subsequent growth of light emitting diode (LED) structures. The treatment procedure included cleaning in organic solvents, organic solvents followed by 5 minutes of HCl, organic solvents and 5 minutes of HCl followed by 2 minutes and finally 10 minutes of HF treatment. Chemical, optical and electrical properties of the surfaces of GaN and InGaN-based LED structures were systematically investigated by x-ray photoemission spectroscopy (XPS), auger electron spectroscopy (AES), atomic force microscopy (AFM), photoluminescence (PL) and electroluminescence (EL) spectroscopy. GaN layers that were grown on the samples treated with HCl and HF showed dramatically different surfaces having high density of 3D structures with high roughness. As measured by AFM, growth of the LED structure on top of the GaN layer continued the 3D-growth mode. LED structures grown on the HCl and HF treated GaN template layers showed minimal to no PL and EL emission and failed after a short period. We suggest a qualitative model of the growth that could potentially explain the underlying phenomena leading to such pronounced changes in the optoelectronic properties and surface conditions of the LED structures due to the treatment of the initial template layers.

Colloidal quantum dot active layer electroluminescence in a solid GaN matrix

2005 ◽  
Vol 891 ◽  
Author(s):  
Jennifer Pagan ◽  
Edward Stokes ◽  
Kinnari Patel ◽  
Casey Burkhart ◽  
Mike Ahrens
Keyword(s):  
Active Layer ◽  
Light Emitting Diode ◽  
Cdse Quantum Dots ◽  
Light Emitting ◽  
Force Microscopy ◽  
Turn On ◽  
Atomic Force ◽  
Transmission Line Method ◽  
Gan Led ◽  
Colloidal Quantum Dot

ABSTRACTIn this paper the preliminary results of incorporating a novel active layer into a GaN light emitting diode (LED) are discussed. Integration of colloidal CdSe quantum dots into a GaN LED active layer is demonstrated. The conductivity of the overgrowth was examined by circular transmission line method (CTLM). Effects on surface roughness due to the active layer incorporation are examined using atomic force microscopy (AFM). LED test devices were fabricated and electroluminescence was demonstrated, the devices exhibit higher turn-on voltages than would be expected for a CdSe active layer.

High Power 330 nm AlInGaN UV LEDs in the High Injection Regime

2003 ◽  
Vol 798 ◽  
Author(s):  
M. Gherasimova ◽  
J. Su ◽  
G. Cui ◽  
J. Han ◽  
H. Peng ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Threading Dislocation ◽  
Light Emitting ◽  
Force Microscopy ◽  
Sapphire Substrates ◽  
Atomic Force ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Dimensional Growth ◽  
Uv Leds

ABSTRACTWe report on the growth and testing of the light emitting diode structures incorporating quaternary AlInGaN active region with an emission wavelength of 330 nm. Small area circular devices were fabricated, yielding the output power of 110 μW measured with a bare-chip configuration in a high current injection regime (8 kA/cm2 for a 20 μm diameter device). Structural properties of the constituent epitaxial layers were evaluated by atomic force microscopy and transmission electron microscopy, resulting in the observation of two-dimensional growth morphologies of AlN and AlGaN, and the estimate of threading dislocation densities in the low 109 cm-2 range in the structures grown on sapphire substrates.

scholarly journals Passive Films and Blistering of Titanium

1999 ◽  
Vol 556 ◽  
Author(s):  
Peter J. Bedrossian ◽  
Joseph C. Farmer ◽  
R. Daniel McCright ◽  
Douglas L. Phinney ◽  
John C. Estill
Keyword(s):  
Electrochemical Cell ◽  
Yucca Mountain ◽  
Passive Films ◽  
Photoemission Spectroscopy ◽  
X Ray ◽  
Force Microscopy ◽  
Hydride Formation ◽  
Atomic Force ◽  
One Year

AbstractCoupons of titanium alloys under consideration as components of the Engineered Barrier System in the proposed repository at Yucca Mountain have been evaluatedfor their passive film composition and stability. Oxide depths and compositions on specimens exposed in long-term corrosion testing for one year were determined with x-ray photoemission spectroscopy. The specimens removed from long-term testing, as well as separate coupons polarized cathodically in an electrochemical cell, exhibited blistering associated with hydride formation in both scanning electron microscopy and atomic force microscopy.

Low Temperature Si Direct Bonding by Plasma Activation

2000 ◽  
Vol 657 ◽  
Author(s):  
Yonah Cho ◽  
Nathan W. Cheung
Keyword(s):  
Surface Energy ◽  
Oxygen Plasma ◽  
Photoemission Spectroscopy ◽  
X Ray ◽  
Force Microscopy ◽  
Plasma Irradiation ◽  
Atomic Force ◽  
Plasma Activation ◽  
Physical Effects ◽  
Si Wafer

ABSTRACTChemical and physical effects of plasma exposed Si wafer pairs were investigated on Si wafer bonding. Oxygen plasma treated Si wafer pairs bonded more strongly at room temperature compared to chemically cleaned, hydrophilic and hydrophobic Si. After 50 hours of annealing at 105°C, the surface energy of the bonded Si pair reached the surface energy of bulk Si (100). X- ray photoemission spectroscopy (XPS) measurements indicated that the exposure of both hydrophilic and hydrophobic Si to oxygen plasma increased a SiO2 like state in the surface layer to a depth of 1.5 nm. Atomic force microscopy (AFM) study showed that plasma irradiation at 300 watts up to 30 seconds did not change surface roughness below 0.5 nm. Exposure to He plasma or N2 did result in enhanced bonding after annealing at 165°C, however, over smaller areas.

Local nanotip arrays sculptured by atomic force microscopy to enhance the light-output efficiency of GaN-based light-emitting diode structures

2014 ◽  
Vol 25 (19) ◽  
pp. 195401 ◽  
Author(s):  
Chun-Ying Huang ◽  
Yung-Chi Yao ◽  
Ya-Ju Lee ◽  
Tai-Yuan Lin ◽  
Wen-Jang Kao ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Light Emitting Diode ◽  
Light Output ◽  
Light Emitting ◽  
Force Microscopy ◽  
Atomic Force ◽  
Output Efficiency

Atomic Structure of Non-Basal-Plane SiC Surfaces: Hydrogen Etching and Surface Phase Transformations

2006 ◽  
Vol 911 ◽  
Author(s):  
Serguei Soubatch ◽  
Wai Y. Lee ◽  
Martin Hetzel ◽  
Chariya Virojanadara ◽  
Camilla Coletti ◽  
...  
Keyword(s):  
Photoemission Spectroscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Hydrogen Etching ◽  
X Ray ◽  
Force Microscopy ◽  
Low Energy Electron Diffraction ◽  
Atomic Force ◽  
Surface Phases ◽  
Low Energy Electron

AbstractA-plane (11-20) and diagonal cut (1-102) and (-110-2) surfaces of 4H-SiC have been investigated using atomic force microscopy (AFM), low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), X-ray photoemission spectroscopy (XPS) and scanning tunneling microscopy (STM). After hydrogen etching the surfaces show large, flat terraces. On SiC(11-20) steps down to single atomic heights are observed. On the diagonal cut surfaces steps run parallel and perpendicular to the [-1101] direction, yet drastically different morphologies for the two isomorphic orientations are found. All surfaces immediately display a sharp LEED pattern. For SiC(1-102) and SiC(-110-2) the additional significant presence of oxygen in the AES spectra indicates the development of an ordered oxide. All three surfaces show an oxygen free, well ordered surface after Si deposition and annealing. A transformation between different surface phases is observed upon annealing.

Structural Characterization of PLD-grown Nanometer Size Ferromagnetic NiFeMo Films

2009 ◽  
Vol 1200 ◽  
Author(s):  
Mitali Banerjee ◽  
Alak Kumar Majumdar ◽  
R J Choudhary ◽  
D M Phase ◽  
S Rai ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Structural Characterization ◽  
Middle Layer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
High Roughness ◽  
Ferromagnetic Bulk ◽  
Single Crystal Sapphire

AbstractThin films of 3 different thicknesses each of Ni83.2Fe3.3Mo13.5 and Ni83.1Fe6.0Mo10.9alloys have been grown using Pulsed Laser Deposition (PLD) technique. Our motivation is to investigate the magnetic properties of a few nm thick Ni alloys with mostly Mo (4d element) addition since the corresponding soft ferromagnetic bulk alloys have shown very small coercivity of ˜ 0.1 Oe. Detailed structural characterization has been undertaken before probing the magnetic properties. Arc melted alloy buttons after homogenization are used directly as targets for the deposition. Films were deposited on single crystal Sapphire (0001) substrates using excimer laser. The structural characterization has been done by X-ray diffraction (XRD), X-ray reflectivity (XRR), Energy dispersive x-ray spectroscopy (EDS), and Atomic force microscopy (AFM). The X-ray diffraction pattern shows that the films are highly textured and grown along [111] direction of the alloys. They have high lattice strain which makes the films highly resistive and the resistance decreases with increasing thickness. The EDS measurements, using Scanning electron microscope (SEM), indicate that the compositions of the films are almost the same as those of the targets. Thickness, roughness, and density gradients are estimated using XRR measurements. The thinner films have higher roughness compared to the thicker ones for both the compositions. The films have density gradient across their thickness. The bottommost low density layer has high roughness which is supposed to be the result of initial non uniform coverage of the substrate. The density of the middle layer, having the lowest roughness, is approximately near the bulk value and it increases with increasing film thickness. The change in density is not due to the variation of composition; instead it is due to the variation of void densities in the layers. The topmost layer, having the lowest density and the highest roughness, is interpreted as a porous layer which is also evident from the AFM images.

scholarly journals Transferable Substrateless GaN LED Chips Produced by Femtosecond Laser Lift-Off for Flexible Sensor Applications

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 891 ◽  
Author(s):  
Nursidik Yulianto ◽  
Steffen Bornemann ◽  
Lars Daul ◽  
Christoph Margenfeld ◽  
Irene Manglano Clavero ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Light Emitting ◽  
Force Microscopy ◽  
Sensor Applications ◽  
Atomic Force ◽  
Lift Off ◽  
Pulse Energies ◽  
Ultrashort Laser

Transferable substrate-less InGaN/GaN light-emitting diode (LED) chips have successfully been fabricated in a laser lift-off (LLO) process employing high power ultrashort laser pulses with a wavelength of 520 nm. The irradiation of the sample was conducted in two sequential steps involving high and low pulse energies from the backside of the sapphire substrate, which led to self-detachment of the GaN stack layer without any additional tape release procedure. To guarantee their optoelectrical function and surface quality, the lifted LED chips were assessed in scanning electron microscopy (SEM) and electroluminescence (EL) measurements. Moreover, surface characterizations were done using atomic force microscopy (AFM) and Auger Electron Spectroscopy (AES).

Scanning Photoemission Spectromicroscopic Study of 4-nm Ultrathin SiO3.4 Protrusions Probe-Induced on the Native SiO2 Layer

2011 ◽  
Vol 17 (6) ◽  
pp. 944-949 ◽  
Author(s):  
Rupesh S. Devan ◽  
Shun-Yu Gao ◽  
Yu-Rong Lin ◽  
Shun-Rong Cheng ◽  
Chia-Er Hsu ◽  
...  
Keyword(s):  
Photoemission Spectroscopy ◽  
Large Area ◽  
Xps Spectra ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Peak Intensity ◽  
Content Ratio ◽  
Si Content ◽  
Chemical Distribution

AbstractAtomic force microscopy probe-induced large-area ultrathin SiOx (x ≡ O/Si content ratio and x > 2) protrusions only a few nanometers high on a SiO2 layer were characterized by scanning photoemission microscopy (SPEM) and X-ray photoemission spectroscopy (XPS). SPEM images of the large-area ultrathin SiOx protrusions directly showed the surface chemical distribution and chemical state specifications. The peak intensity ratios of the XPS spectra of the large-area ultrathin SiOx protrusions provided the elemental quantification of the Si 2p core levels and Si oxidation states (such as the Si4+, Si3+, Si2+, and Si1+ species). The O/Si content ratio (x) was evidently determined by the height of the large-area ultrathin SiOx protrusions.

scholarly journals Electroplating of Semiconductor Materials for Applications in Large Area Electronics: A Review

Coatings ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 262 ◽  
Author(s):  
Ayotunde Adigun Ojo ◽  
Imyhamy Mudiy Dharmadasa
Keyword(s):  
Low Cost ◽  
Photoelectrochemical Cell ◽  
X Ray Diffraction ◽  
Large Area ◽  
X Ray ◽  
Force Microscopy ◽  
Treatment Processes ◽  
Atomic Force ◽  
Optical And Electronic Properties ◽  
Device Applications

The attributes of electroplating as a low-cost, simple, scalable, and manufacturable semiconductor deposition technique for the fabrication of large-area and nanotechnology-based device applications are discussed. These strengths of electrodeposition are buttressed experimentally using techniques such as X-ray diffraction, ultraviolet-visible spectroscopy, scanning electron microscopy, atomic force microscopy, energy-dispersive X-ray spectroscopy, and photoelectrochemical cell studies. Based on the results of structural, morphological, compositional, optical, and electronic properties evaluated, it is evident that electroplating possesses the capabilities of producing high-quality semiconductors usable for producing excellent devices. In this paper we will describe the progress of electroplating techniques mainly for the deposition of semiconductor thin film materials and their treatment processes, and fabrication of solar cells.

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