Properties and Growth of MBE Grown Erbium Doped Gallium Arsenide Co-Doped with Selenium

1996 ◽  
Vol 422 ◽  
Author(s):  
P. Rutter ◽  
K. E. Singer ◽  
A. R. Peaker ◽  
A. C. Wright
Keyword(s):  
Electron Concentration ◽  
Flux Ratio ◽  
Growth Conditions ◽  
Deep Levels ◽  
Spherical Particles ◽  
Electrical Measurements ◽  
Erbium Doping ◽  
Measured Concentration ◽  
Erbium Doped ◽  
Co Doped

AbstractThe growth of erbium doped GaAs by molecular beam epitaxy (MBE) can, depending on growth conditions, result in the precipitation of small spherical particles of erbium arsenide. It has been observed that by reducing the V:III (As:Ga) flux ratio to close to stoichiometry wirelike precipitates roughly aligned in the direction of growth are produced. The concentration of erbium incorporated into the GaAs lattice for a constant erbium flux is also affected by the As:Ga flux ratio with an increase in erbium doping being observed with decreasing As:Ga flux ratio.Electrical measurements have been performed on erbium doped GaAs samples co-doped with selenium, an n-type dopant. Measurements have revealed that when erbium is present, the electron concentration is reduced by an amount approximately equal to 70% of the erbium concentration. DLTS measurements have shown that although large concentrations of deep levels are present in erbium doped material, the measured concentration of these deep levels is not high enough to account for the observed reduction in electron concentration with erbium doping.

Properties of Thick n- and p-Type Epitaxial Layers of 4H-SiC Grown by Hot-Wall CVD on Off- and On-Axis Substrates

2006 ◽  
Vol 527-529 ◽  
pp. 183-186 ◽  
Author(s):  
Jawad ul Hassan ◽  
Christer Hallin ◽  
Peder Bergman ◽  
Erik Janzén
Keyword(s):  
Material Properties ◽  
Carrier Lifetime ◽  
Growth Conditions ◽  
Deep Levels ◽  
Growth Time ◽  
Epitaxial Layers ◽  
Electrical Measurements ◽  
P Type ◽  
Thick Layers

Thick epitaxial layers of 4H-SiC both n- and p-type were grown using horizontal Hot- Wall CVD (HWCVD). No large difference in the carrier lifetime was observed for the layers grown on n- and p-type substrates. The carrier lifetime usually increases with the increasing thickness of the epilayer. To investigate if the growth conditions and material properties are changing during the longer growth time a sample was prepared with uniformly varying epilayer thickness from 20μm on one side to 110μm on other side. Results of optical and electrical measurements, the variation in background impurities and other deep levels are discussed. Furthermore, the properties of thick layers grown on on-axis substrates are presented.

Effect of N/Ga Flux Ratio in GaN Buffer Layer Growth by MBE on (0001) Sapphire on Defect Formation in the GaN Main Layer

1999 ◽  
Vol 572 ◽  
Author(s):  
S. Ruvimov ◽  
Z. Liliental-Weber ◽  
J. Washburn ◽  
Y. Kim ◽  
G. S. Sudhir ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Buffer Layer ◽  
Defect Formation ◽  
Flux Ratio ◽  
Growth Conditions ◽  
Buffer Layers ◽  
Simultaneous Increase ◽  
Growth Stages ◽  
Dislocation Generation ◽  
Gan Buffer Layer

ABSTRACTTransmission electron microscopy was employed to study the effect of N/Ga flux ratio in the growth of GaN buffer layers on the structure of GaN epitaxial layers grown by molecular-beamepitaxy (MBE) on sapphire. The dislocation density in GaN layers was found to increase from 1×1010 to 6×1010 cm−2 with increase of the nitrogen flux from 5 to 35 sccm during the growth of the GaN buffer layer with otherwise the same growth conditions. All GaN layers were found to contain inversion domain boundaries (IDBs) originated at the interface with sapphire and propagated up to the layer surface. Formation of IDBs was often associated with specific defects at the interface with the substrate. Dislocation generation and annihilation were shown to be mainly growth-related processes and, hence, can be controlled by the growth conditions, especially during the first growth stages. The decrease of electron Hall mobility and the simultaneous increase of the intensity of “green” luminescence with increasing dislocation density suggest that dislocation-related deep levels are created in the bandgap.

scholarly journals Phase Selectivity in Cr and N Co-Doped TiO2 Films by Modulated Sputter Growth and Post-Deposition Flash-Lamp-Annealing

Coatings ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 448 ◽  
Author(s):  
Raúl Gago ◽  
Slawomir Prucnal ◽  
René Hübner ◽  
Frans Munnik ◽  
David Esteban-Mendoza ◽  
...  
Keyword(s):  
Single Phase ◽  
Functional Materials ◽  
Growth Conditions ◽  
Anatase Tio2 ◽  
Flash Lamp ◽  
Interface Engineering ◽  
Doped Tio2 ◽  
Phase Selectivity ◽  
Post Deposition ◽  
Co Doped

In this paper, we report on the phase selectivity in Cr and N co-doped TiO2 (TiO2:Cr,N) sputtered films by means of interface engineering. In particular, monolithic TiO2:Cr,N films produced by continuous growth conditions result in the formation of a mixed-phase oxide with dominant rutile character. On the contrary, modulated growth by starting with a single-phase anatase TiO2:N buffer layer, can be used to imprint the anatase structure to a subsequent TiO2:Cr,N layer. The robustness of the process with respect to the growth conditions has also been investigated, especially regarding the maximum Cr content (<5 at.%) for single-phase anatase formation. Furthermore, post-deposition flash-lamp-annealing (FLA) in modulated coatings was used to improve the as-grown anatase TiO2:Cr,N phase, as well as to induce dopant activation (N substitutional sites) and diffusion. In this way, Cr can be distributed through the whole film thickness from an initial modulated architecture while preserving the structural phase. Hence, the combination of interface engineering and millisecond-range-FLA opens new opportunities for tailoring the structure of TiO2-based functional materials.

Sensing behavior of perovskites GdCo1−xCuxO3 prepared by solution and ultrasonic-assisted aerosol methods.

2004 ◽  
Vol 828 ◽  
Author(s):  
Carlos R. Michel ◽  
Edgar R. López ◽  
Arturo Chávez
Keyword(s):  
Aqueous Solutions ◽  
Solution Method ◽  
Spherical Particles ◽  
Electrical Measurements ◽  
Gas Sensitivity ◽  
Semiconductor Behavior ◽  
Ultrasonic Assisted ◽  
Method Yield ◽  
Precursor Powders ◽  
Made In

ABSTRACTPolycrystalline samples of GdCo1−xCuxO3 (x=0, 0.15, 0.3), were prepared by two different routes: solution and ultrasonic-assisted aerosol decomposition. For both procedures, aqueous solutions containing stoichiometric amounts of Gd(NO3)36H2O, Co(NO3)26H2O and Cu(NO3)22.5H2O were used. In the solution method, the aqueous solutions were heat-dried at 76°C obtaining precursor powders, these were calcined from 80 to 950°C, in air. In the aerosol method, very small droplets were produced by an ultrasonic generator, then a flow of oxygen transported the mist through a tubular furnace, previously heated at 950°C. Solvent evaporation and chemical reaction takes place at that temperature, and the resulting powder was collected by filtration. X-ray powder diffraction was used to identify the formation of target phases. Surface microstructure of powders was analyzed by SEM, and showed that solution method produced sub-micron particles with irregular shape, whereas the aerosol method yield micron-sized hollow spherical particles. In order to determine gas sensitivity vs. temperature, electrical measurements were made in air, O2 and CO2, from room temperature to 650°C. The results showed a semiconductor behavior and a moderate gas sensitivity for samples prepared by solution method. However, unreliable data were registered for samples made by the aerosol route, caused by short connectivity between particles.

Electron concentration in highly resistive GaN substrates co-doped with Si, C, and Fe

2018 ◽  
Vol 57 (7) ◽  
pp. 071001 ◽  
Author(s):  
Hirokuni Tokuda ◽  
Kosuke Suzuki ◽  
Joel T. Asubar ◽  
Masaaki Kuzuhara
Keyword(s):  
Electron Concentration ◽  
Co Doped

scholarly journals Effect of Buffer Layer and III/V Ratio on the Surface Morphology of Gan Grown by MBE

1999 ◽  
Vol 4 (S1) ◽  
pp. 417-422 ◽  
Author(s):  
E. C. Piquette ◽  
P. M. Bridger ◽  
R. A. Beach ◽  
T. C. McGill
Keyword(s):  
Surface Morphology ◽  
Buffer Layer ◽  
Flux Ratio ◽  
Plasma Source ◽  
Growth Conditions ◽  
Nitrogen Plasma ◽  
Layer Growth ◽  
Buffer Layers ◽  
Flat Surfaces ◽  
Aln Buffer

The surface morphology of GaN is observed by atomic force microscopy for growth on GaN and AlN buffer layers and as a function of III/V flux ratio. Films are grown on sapphire substrates by molecular beam epitaxy using a radio frequency nitrogen plasma source. Growth using GaN buffer layers leads to N-polar films, with surfaces strongly dependent on the flux conditions used. Flat surfaces can be obtained by growing as Ga-rich as possible, although Ga droplets tend to form. Ga-polar films can be grown on AlN buffer layers, with the surface morphology determined by the conditions of buffer layer deposition as well as the III/V ratio for growth of the GaN layer. Near-stoichiometric buffer layer growth conditions appear to support the flattest surfaces in this case. Three defect types are typically observed in GaN films on AlN buffers, including large and small pits and “loop” defects. It is possible to produce surfaces free from large pit defects by growing thicker films under more Ga-rich conditions. In such cases the surface roughness can be reduced to less than 1 nm RMS.

Electrical And Structural Properties Of LT-GaAs: Influence Of As/Ga Flux Ratio And Growth Temperature

1996 ◽  
Vol 442 ◽  
Author(s):  
M. Luysberg ◽  
H. Sohn ◽  
A. Prasad ◽  
P. Specht ◽  
H. Fujioka ◽  
...  
Keyword(s):  
Structural Properties ◽  
Point Defects ◽  
Growth Temperature ◽  
Conduction Mechanism ◽  
Growth Parameters ◽  
Flux Ratio ◽  
Growth Conditions ◽  
High Resistivity ◽  
Antisite Defects ◽  
Band Conduction

AbstracThe deposition of GaAs by MBE at low temperatures results in a material of unique properties. However, up to now the control and understanding of the electrical and structural properties are unsatisfactory. To investigate the influence of growth parameters on the formation of point defects and electrical properties, the substrate temperature and the As/Ga flux ratio were systematically varied. In a well defined parameter range the lattice expansion was found to be dominated by the formation of As antisite defects. After annealing a high resistivity is obtained independent of the growth conditions. A strong influence of the growth temperature on the band conduction mechanism is observed, whereas a variation of the As/Ga flux ratio induces only slight changes of the temperature dependence of the conductivity.

About the Electrical and Structural Properties of Erbium Thermally Diffused in Single Crystal Silicon

1996 ◽  
Vol 422 ◽  
Author(s):  
S. Binetti ◽  
M. Acciarri ◽  
I. Gelmi ◽  
S. Pizzini
Keyword(s):  
Electrical Properties ◽  
Chemical Analysis ◽  
Silicon Substrate ◽  
Silica Glass ◽  
Single Crystal Silicon ◽  
Auger Spectroscopy ◽  
Erbium Oxide ◽  
Erbium Doping ◽  
Crystal Silicon ◽  
Erbium Doped

AbstractHaving preliminary confirmed the possibility of erbium doping by thermal diffusion, we have used this process to introduce erbium into a silicon substrate from metallic erbium or erbium oxide sources. Diffusion experiments were carried out at 1050, 1200 and 1250°C. The Er:Si diffused samples were investigated using four probe resistivity and thermopower techniques for the measure of the concentration and type of carriers, SIMS and Auger spectroscopy for chemical analysis of the diffused layers and photoluminescence (PL) measurements at temperatures ranging from 2 to 298 K for the detection of optical activity. None of the samples prepared presented measurable PL at 2 K, except for one single sample on top of which was deposited an erbium doped silica glass. The electrical properties, instead, were deeply influenced by doping, indicating the formation of both donor and acceptors.

Peculiarities of axial and radial Ge–Si heterojunction formation in nanowires: Monte Carlo simulation

2012 ◽  
Vol 84 (12) ◽  
pp. 2619-2628 ◽  
Author(s):  
Nataliya L. Shwartz ◽  
Alla G. Nastovjak ◽  
Igor G. Neizvestny
Keyword(s):  
Monte Carlo ◽  
Small Diameter ◽  
Chemical Species ◽  
Flux Ratio ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Drop Diameter ◽  
Nanowire Diameter ◽  
Mc Simulation ◽  
Drop Composition

The process of axial and radial Si–Ge heterostructure formation during nanowire growth by vapor–liquid–solid (VLS) mechanism was studied using Monte Carlo (MC) simulation. It was demonstrated that radial growth can be stimulated by adding chemical species that decrease the activation energy of precursor dissociation or the solubility of semiconductor material in catalyst drop. Reducing the Si adatom diffusion length also leads to Si shell formation around the Ge core. The influence of growth conditions on the composition and abruptness of axial Ge–Si heterostructures was analyzed. The composition of the GexSi1–x axial heterojunction (HJ) was found to be dependent on the flux ratio, the duration of Si and Ge deposition, and the catalyst drop diameter. Maximal Ge concentration in the HJ is dependent on Ge deposition time owing to gradual changing of catalyst drop composition after switching Ge and Si fluxes. The dependence of junction abruptness on the nanowire diameter was revealed: in the adsorption-induced growth mode, the abruptness decreased with diameter, and in the diffusion-induced mode it increased. This implies that abrupt Ge–Si HJ in nanowires with small diameter can be obtained only in the chemical vapor deposition (CVD) process with negligible diffusion component of growth.

MICROSTRUCTURE AND OPTICAL PROPERTIES OF ERBIUM DOPED SILICA-BASED FILMS VIA FLAME HYDROLYSIS DEPOSITION AND AEROSOL DOPING

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1873-1878 ◽  
Author(s):  
JIEHE SUI ◽  
HAIBO WANG ◽  
WEI CAI
Keyword(s):  
Solution Concentration ◽  
Concentration Quenching ◽  
Power Intensity ◽  
Erbium Ions ◽  
Erbium Doped ◽  
Doping Technique ◽  
Cooperative Upconversion ◽  
Pl Intensity ◽  
Flame Hydrolysis Deposition ◽  
Co Doped

Silica-based films on Si fabricated by flame hydrolysis deposition were doped with erbium ions using an aerosol doping technique, and co-doped with GeO 2, P 2 O 5 and B 2 O 3. The erbium solution concentration was varied from 4 to 8wt%. The results show that the refractive index of the films is not changed with erbium addition and no OH group is detected for erbium doped silica-based films. An obvious peak was observed at 1.542 µm with the FWHM of 65 nm, which corresponds to the 4 I 13/2 → 4 I 15/2 transition. With the increase of Er solution concentration, the photoluminescence (PL) intensity first increases, then decreases above 6 wt % Er solution concentration. The decrease in PL intensity with concentration is attributed to concentration quenching caused by Er - Er interaction. The dependence of PL intensity on pump power intensity further confirms the concentration quenching is cooperative upconversion.

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