Detection of Crystallographic Defects in 3C-SiC by Micro-Raman and Micro-PL Analysis

2017 ◽  
Vol 897 ◽  
pp. 303-306 ◽  
Author(s):  
Grazia Litrico ◽  
Nicolò Piluso ◽  
Francesco La Via
Keyword(s):  
High Power ◽  
Longitudinal Optical ◽  
Epitaxial Films ◽  
Raman Shift ◽  
Extended Defects ◽  
Free Carriers ◽  
Coupled Mode ◽  
Pl Emission ◽  
A New Technique ◽  
Crystallographic Defects

A new technique with micro-Raman and micro-PL analysis is proposed to detect defects in 3C-SiC epitaxial films. The high-power of an above band-gap laser is used to increase locally the free carriers density in un-doped epitaxial material (n < 1016 cm-3). The electronic plasma couples with the longitudinal optical (LO) Raman mode determining the so-called LOPC effect. The Raman shift of the LO phonon-plasmon-coupled mode (LOPC) changes as the free carriers density is modified. Crystallographic defects induce a modification of the free carriers density determining a change in the Raman shift of LO mode and in the PL emission from the 3C-SiC gap. Thus we suppose that the results observed are connected to crystallographic defects and we propose this technique as a methodology to analyze extended defects in 3C-SiC material because a detailed study of defects in 3C-SiC has not yet been performed.

4H-SiC Defects Analysis by Micro Raman Spectroscopy

2015 ◽  
Vol 821-823 ◽  
pp. 335-338 ◽  
Author(s):  
Nicolo’ Piluso ◽  
Massimo Camarda ◽  
Ruggero Anzalone ◽  
Francesco La Via
Keyword(s):  
Longitudinal Optical ◽  
Stacking Fault ◽  
Raman Signal ◽  
Extended Defects ◽  
Free Carriers ◽  
Laser Pumping ◽  
Spatial Morphology ◽  
Defects Analysis ◽  
Crystallographic Defects

Recently, a new Micro-Raman technique has been used to detect extended defects in 4H-SiC homoepitaxy. The method is based on the local increase of free carriers in undoped epitaxies (n < 1016 at/cm-3) produced by a high power laser. The Longitudinal optical Raman mode (LO) is coupled with the electronic plasma generated by the laser pumping; such a Raman signal is sensitive to crystallographic defects that lead to trapping (or dispersion) of the free carriers which results in a loss of coupling. The monitoring of the LOPC allows determining the spatial morphology of extended defects. The results show that the detection of defects via the induced-LOPC (i-LOPC) is totally independent from the stacking fault photoluminescence signals that cover a large energy range up to 0,7eV thus allowing for a single-scan simultaneous determination of any kind of stacking fault. Also, the i-LOPC method shows the connection between the carrier concentration and the carrier lifetime for undoped film, obtaining meaningful information related to electrical properties of the film, and demonstrating that this technique is a fast, reliable and powerful method to characterize most of crystallographic defects (extended and point-like defects) in the semiconductor field.

CL/EBIC-SEM Techniques for Evaluation of Impact of Crystallographic Defects on Carrier Lifetime in 4H-SiC Epitaxial Layers

2010 ◽  
Vol 645-648 ◽  
pp. 211-214 ◽  
Author(s):  
Serguei I. Maximenko ◽  
Jaime A. Freitas ◽  
Yoosuf N. Picard ◽  
Paul B. Klein ◽  
Rachael L. Myers-Ward ◽  
...  
Keyword(s):  
Carrier Lifetime ◽  
Stacking Faults ◽  
Epitaxial Films ◽  
Charge Collection ◽  
Induced Current ◽  
Edge Type ◽  
Electron Beam Induced Current ◽  
Recombination Centers ◽  
Crystallographic Defects ◽  
And Diffusion

The effect of various types of in-grown stacking faults and threading screw/edge type dislocations on carrier lifetime and diffusion lengths in 4H-SiC epitaxial films was investigated through cathodoluminescence decays and charge collection efficiencies of electron beam induced current signals at specific defects sites. Most stacking faults yielded ~40% reduction in the carrier lifetime. Moreover, drastic lifetime reductions were observed in regions containing surface triangular defects and bulk 3C polytype inclusions. Dislocations of both types serve as efficient recombination centers, though stronger reduction in diffusion lengths was observed in the vicinity of screw type dislocations.

Optical Probe in MgZnO Alloys with Varied Mg Ratios by Metalorganic Chemical Vapor Deposition

2013 ◽  
Vol 746 ◽  
pp. 406-410 ◽  
Author(s):  
Xiang Ping Shu ◽  
Cheng Chen ◽  
Yi Ting He ◽  
Zhi Ren Qiu ◽  
Dong Sing Wuu ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Chemical Vapor ◽  
Optical Probe ◽  
Longitudinal Optical ◽  
Raman Shift ◽  
Measured Temperature ◽  
Temperature Range ◽  
Metalorganic Chemical

We present a study on five MgxZn1-xO samples with varied x (x = 0, 0.01, 0.06, 0.10 and 0.14), grown on sapphire substrate by Metalorganic Chemical Vapor Deposition (MOCVD). Combined photoluminescence (PL) and Raman scattering studies were carried out over a temperature range of 80K-470K, under the excitation of UV 325 nm. Temperature dependence of the PL for MgZnO with x = 0, 0.01 and 0.06 are shown. The resonance Raman longitudinal optical (LO) multiple modes are exhibited for MgZnO with x = 0.06, 0.10 and 0.14 over all temperature range. Raman shifts exhibit a quadratic dependence on temperature in the measured temperature range. These dependences can be calculated, based upon a model involving three-and four-phonon coupling. We attribute both the thermal expansion and four-phonon terms in the four-phonon anharmonic processes to describe the change of Raman shift with temperature.

Gettering of Dissolved and Segregated Impurities in Multicrystalline Silicon Wafers

1992 ◽  
Vol 262 ◽  
Author(s):  
M. Stemmer ◽  
I. Perichaud ◽  
S. MartiNuzzi
Keyword(s):  
Grain Boundaries ◽  
Light Beam ◽  
Minority Carrier ◽  
Diffusion Length ◽  
Extended Defects ◽  
Induced Current ◽  
Minority Carrier Diffusion Length ◽  
Cast Ingot ◽  
Crystallographic Defects ◽  
Homogeneous Regions

ABSTRACTPhosphorus gettering by diffusion from a POCl3 source was applied to matched wafers cut out of the same region of a cast ingot. Light Beam Induced Current mappings with wavelengths in the range between 840 and 980 nm lead to follow the variation of minority carrier diffusion length after gettering at 900°C for 120 and 240 mn, especially near extended crystallographic defects like dislocations and grain boundaries.The mappings show that after the gettering treatments, the local values of L increase due to the reduction of the recombination strength of extended defects and to the improvement of the homogeneous regions of the grains.As SIMS analyses indicate that Fe, Cu and Ni atoms are gettered, it is reasonable to assume that these impurities were initially dissolved in the grains and also segregated at the extended defects.

Raman Scattering and Photoluminescence of Mg Doped GaN Films Grown by Molecular Beam Epitaxy

1997 ◽  
Vol 468 ◽  
Author(s):  
G. Popovici ◽  
G. Y. Xu ◽  
A. Botchkarev ◽  
W. Kim ◽  
H. Tang ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Tensile Stress ◽  
Molecular Beam ◽  
Growth Conditions ◽  
Longitudinal Optical ◽  
Raman Shift ◽  
Longitudinal Optical Phonon ◽  
Photoluminescence Peak ◽  
Mg Doped

ABSTRACTRaman, photoluminescence, and Hall measurements are reported for Mg doped GaN films grown by molecular beam epitaxy. The compressive and tensile stress determined by the Raman shift of the phonon lines is due to the growth conditions rather than the presence of Mg in the film. The photoluminescence peak of near band-to-band transitions is also shifted to larger (smaller) energies by the compressive (tensile) stress. The study of the longitudinal optical phonon of the Ai branch shows that its Raman line shape is affected not only by phonon-plasmon interactions but by the crystalline quality of the film, as well.

Exciton Spectra of AlN Epitaxial Films

2001 ◽  
Vol 693 ◽  
Author(s):  
T. Onuma ◽  
S. F. Chichibu ◽  
T. Sota ◽  
K. Asai ◽  
S. Sumiya ◽  
...  
Keyword(s):  
Sapphire Substrate ◽  
Characteristic Temperature ◽  
Longitudinal Optical ◽  
Epitaxial Films ◽  
Longitudinal Optical Phonon ◽  
Bohr Radius ◽  
Spectral Lineshape ◽  
Resonance Energies ◽  
Excitonic Emission ◽  
Excitonic Resonance

AbstractExcitonic resonance energies in a C-plane AlN epilayer on the (0001) sapphire substrate grown by low-pressure metalorganic vapor phase epitaxy were determined as a function of temperature by means of optical reflectance (OR) and cathodoluminescence (CL) measurements. The OR spectra exhibited distinct reflectance anomalies at the photon energies just above the multiple internal reflection fringes, and the spectral lineshape was fitted considering A (???u7v7c) and BC (???9v,???17v7c) exciton transitions. The energies of them at 0 K were obtained to be 6.211 and 6.266 eV, giving the crystal field splitting (Δcr) of approximately 55 meV. The AlNfilm exhibited an excitonic emission even at 300 K, which is due to the small Bohr radius of excitons and large longitudinal optical phonon energies. The Einstein characteristic temperature Q E was estimated to be 580 K.

Longitudinal-optical phonon hole-plasmon coupled modes in heavily doped p-type GaSb:Zn epitaxial films

2006 ◽  
Vol 50 (3) ◽  
pp. 403-410
Author(s):  
Z. G. Hu ◽  
M. B.M. Rinzan ◽  
A. G.U. Perera ◽  
Y. Paltiel ◽  
A. Raizman ◽  
...  
Keyword(s):  
Optical Phonon ◽  
Longitudinal Optical ◽  
Epitaxial Films ◽  
Longitudinal Optical Phonon ◽  
Coupled Modes ◽  
Heavily Doped ◽  
P Type

scholarly journals Нерезонансное обращение волнового фронта света в оптически возбужденных пленках ZnO

2020 ◽  
Vol 54 (8) ◽  
pp. 700
Author(s):  
А.Н. Грузинцев
Keyword(s):  
Photon Energy ◽  
Spectral Region ◽  
Signal Intensity ◽  
Room Temperature ◽  
Phase Conjugation ◽  
Epitaxial Films ◽  
Nitrogen Laser ◽  
Free Carriers ◽  
Laser Pumping ◽  
Infrared Spectral

The opportunity of the nonresonant phase conjugation of light (NPC) in the excited semiconductor was shown theoretical and experimental. The induced NPC of light in the visibal and infrared spectral region was detected on the ZnO epitaxial films at room temperature by nitrogen laser pumping. The dependences of the NPC signal intensity on its photon energy and on the intensity of laser pumping were investigated. This effect explanation was given: change of absorption and refraction of the light on the laser induced free carriers in the semiconductor.

A new technique for measuring size distributions of fine ingesta/digesta particles

2000 ◽  
Vol 27 (2) ◽  
pp. 191 ◽  
Author(s):  
Murray Logan ◽  
Gordon D. Sanson
Keyword(s):  
Image Analysis ◽  
High Power ◽  
Focal Plane ◽  
Constant Volume ◽  
New Technique ◽  
Size Distributions ◽  
Small Particles ◽  
Microscope Slide ◽  
Food Material ◽  
A New Technique

Techniques were developed to enable convenient, high-power image analysis of (ingested) food material. A constant volume of diluted gut sample was delivered to a large microscope slide before being slowly evaporated in still air to leave all particles statically on the same focal plane. Evaporation also allowed a meniscus to develop around each particle, forcing them to separate and thereby preventing overlap and aggregation of particles. Sub-samples were measured under four high-power magnifications (2050, 1290, 510 and 190) to permit precise estimates of size distributions of the very small particles. The techniques developed avoid the need for large ingesta/digesta samples, sieving, and filtering, all of which have limited previous studies.

Effect of Cd Substitution on Structural and Optical Properties of Zn1-xCdxSe Thin Films

2021 ◽  
Vol 1039 ◽  
pp. 382-390
Author(s):  
Arej Kadhim ◽  
Mustafa Kadhim ◽  
Haslan Abu Hassan
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Longitudinal Optical ◽  
Raman Shift ◽  
Longitudinal Optical Phonon ◽  
Phonon Modes ◽  
Elemental Ratios ◽  
X Ray ◽  
Cdse Thin Film ◽  
Yellow Region

In this research, Zn1-xCdxSe alloys (x from 0 to 1) were synthesized by solid-state microwave (SSM) method of producing thermally evaporated thin films. The cubic structure and the elemental ratios of the films were studied using X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The optical characterizations of the as-deposited film in terms of the energy band gap (Eg), photoluminescence (PL), and Raman shift spectra were conducted at the room temperature. The Eg values for the thin films from ZnSe to CdSe were 3.4 to 1.7 eV, respectively. The PL orange emission for ZnSe thin film at 565 nm, whereas 590 nm in the yellow region for CdSe thin film. From Raman shift spectra, the two longitudinal-optical phonon modes (1LO and 2LO) at 240, and 490 cm-1 are assigned for the ZnSe and CdSe thin films.

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