Microstructure and Hydrogen Dynamics in a-Si1-xCx:H

1999 ◽  
Vol 557 ◽  
Author(s):  
R. Shinar ◽  
J. Shinar ◽  
D. L. Williamson ◽  
S. Mitra ◽  
H. Kavak ◽  
...  
Keyword(s):  
Electron Cyclotron Resonance ◽  
Secondary Ion Mass Spectrometry ◽  
Total Content ◽  
Relaxation Processes ◽  
Fast Diffusion ◽  
X Ray Scattering ◽  
Boron Doped ◽  
Sputter Deposited ◽  
Hydrogenated Amorphous ◽  
Secondary Ion

AbstractSmall angle x-ray scattering (SAXS), IR spectroscopy, and deuterium secondary ion mass spectrometry (DSIMS) were used to study the microstructure and hydrogen dynamics of undoped and boron-doped if-sputter-deposited (RFS) and electron cyclotron resonance (ECR)-deposited hydrogenated amorphous silicon carbides (a-Si1-xCx:H) with x ≤ 19 at.%. The SAXS measurements indicated residual columnar-like features and roughly spherical nanovoids of total content CnV ≤ 1.0 vol.%. The growth of CnV with annealing was due largely to an increase in the average nanovoid radius. It was noticeably smaller than in RFS a-Si:H films. The IR spectra demonstrated H transfer by annealing from mostly bulk-like Si-H groups to C-bonds. The H diffusion and its temperature dependence in undoped films resembled those of a-Si:H and were consistent with the SAXS and IR data. Suppression of long-range motion of most of the H atoms, consistent with increased CnV was observed in B-doped ECR films. However, a small fraction of the H atoms appeared to undergo fast diffusion, reminiscent of the fast diffusion in doped a-Si:H. The results are consistent with impeded relaxation processes of the Si network, caused by the presence of C atoms, and H trapping at C-H bonds.

IR and Sims Study of Hydrogen Diffusion in RF Sputter Deposited Boron Doped a-Si:H and Undoped a-Ge:H

1989 ◽  
Vol 149 ◽  
Author(s):  
S. Mitra ◽  
X.-L. Wu ◽  
R. Shinar ◽  
J. Shinar
Keyword(s):  
Hydrogen Diffusion ◽  
Secondary Ion Mass Spectrometry ◽  
Stretch Vibration Band ◽  
Vibration Band ◽  
Boron Doped ◽  
Multiple Trapping ◽  
Stretch Vibration ◽  
Order Of Magnitude ◽  
Sputter Deposited ◽  
Secondary Ion

ABSTRACTSecondary ion mass spectrometry (SIMS) and IR measurements of long range deuterium motion in rf sputter deposited (rf sp) p-doped a-Si:H and undoped a-Ge:H are compared to recently published results on undoped rf sp a-Si:H, which exhibited strongly power-law time dependent diffusion constants (exponent α= 0.75±0.1) in films of as-deposited content of di-H and tri-H bonds (usually associated with microvoids) Ndo –4–5 at.%. In pdoped a-Si:H samples where Ndo-l.8–3.8at.%, the diffusion is much faster, but the exponent is similar. In undoped a-Ge:H exhibiting a stretch vibration band indicative of mono-H bonding only, the diffusion is about one order of magnitude faster than in undoped a-Si:H, and α = 0.23. The results are discussed in relation to both the multiple trapping (dispersive) and defect mediated diffusion models.

Hydrogen Diffusion in Undoped and B-Doped a-Si1-xCx:H

1994 ◽  
Vol 336 ◽  
Author(s):  
R. Shinar ◽  
J. Shinar ◽  
G. Subramania ◽  
H. Jia ◽  
S. Sankaranarayanan ◽  
...  
Keyword(s):  
Hydrogen Diffusion ◽  
Electron Cyclotron Resonance ◽  
Secondary Ion Mass Spectrometry ◽  
Diffusion Constant ◽  
Fast Diffusion ◽  
Carrier Recombination ◽  
Boron Doped ◽  
Stretch Vibration ◽  
B Doping ◽  
Resonance Plasma

ABSTRACTA deuterium secondary ion mass spectrometry (SIMS) study of hydrogen diffusion in undoped and boron-doped a-Si0.86C0.4:H deposited by an electron cyclotron resonance plasma is described. The undoped films deposited at 250°C clearly indicated deuterium-hydrogen interdiffusion at T ≥ 350°C. The dispersion parameter a of the power-law time dependent diffusion constant D = D00(ωt)−α decreased from ∼0.3 at T = 350 and 400°C to ∼0.1 at 450°C, and the activation energy for a diffusion length of 1000 Å was ∼1.0 eV. These results are discussed in relation to previous studies of a-Si:H. The diffusion in ∼0.2 and ∼0.6 at.% B-doped a-Si0.86C0.14:H sharply differs from that in B-doped a-Si:H, where an enhancement of up to ∼103 was previously observed. In doped a-Si0.86C0.14:H, the diffusion of most of the H atoms is strongly suppressed, but a small fraction undergoes fast diffusion. IR Measurements indicate that the B-doping reduces the bulk-like Si-H stretch vibration at ∼2000 cm1. Upon annealing, the Si-CHn and C-H wag modes at ∼780 and ∼1000 cm−1, resp., increase, while the 640 and ∼2000 cm1 Si-H wag and stretch modes, resp., weaken, indicating transfer of hydrogen from Si- to C-bonds, in which the H atoms are apparently deeply trapped. As in a-Si:H, the fast diffusion component is apparently due to carrier recombination-enhanced weak Si-Si bond breaking. The results suggest that B-doping also induces microvoids and enhances the rate of breaking of weak Si-C bonds, leading to enhanced trapping of H.

TEM observations of hydrogen nanobubbles in implanted amorphous silicon

1996 ◽  
Vol 54 ◽  
pp. 972-973
Author(s):  
K.M. Jones ◽  
D.L. Williamson ◽  
S. Acco ◽  
M.M. Al-Jassim
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Solubility Limit ◽  
X Rays ◽  
Structural Morphology ◽  
X Ray Scattering ◽  
Structural Probes ◽  
Hydrogenated Amorphous ◽  
Secondary Ion ◽  
Deposited Films

Over the last two decades extensive studies on the optical and electrical properties of hydrogenated amorphous Si (a-Si:H) have been reported. However, less attention was given to the structural characterization of this material partly due to the insensitivity to hydrogen of structural probes such as x-rays and electron diffraction. From a recent set of experiments, results on the solubility limit of hydrogen in a special type of a-Si:H and the characterization of hydrogen induced complexes or nanobubbles has been reported. In this study, we report TEM observations of the structural morphology ofhydrogen related defects that support these recent measurements obtained by secondary ion mass spectrometry (SIMS) and small-angle x-ray scattering (SAXS).a-Si:H thin films for solar cells and other applications are produced by a variety of methods. In each case, the deposited films are usually not homogeneous as they have been found to contain low density inhomogenities in the size range of 1-10 nm. These defects are commonly referred to as microvoids or hydrogen-rich clusters.

Investigation of the Dopant Distribution in thin Epitaxial Silicon Layers by Means of Spreading Resistance Probe and Secondary Ion Mass Spectrometry

1997 ◽  
Vol 500 ◽  
Author(s):  
Ilya Karpov ◽  
Catherine Hartford ◽  
Greg Moran ◽  
Subramania Krishnakumar ◽  
Ron Choma ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Chemical Vapor ◽  
Doping Profile ◽  
Epitaxial Silicon ◽  
Spreading Resistance ◽  
Boron Doped ◽  
Ion Mass Spectrometry ◽  
Chemical Profiles ◽  
Secondary Ion

ABSTRACTIn this paper, we examine the dopant distributions in 1.8 to 4 micron-thick boron- and phosphorus-doped epitaxial silicon layers. These layers were grown by chemical vapor deposition (CVD) on arsenic-, antimony-, or boron-doped (100)- and (111)-oriented substrates. We performed doping profile studies by means of local resistivity measurements using a spreading resistance probe (SRP). Chemical profiles of the dopants were also obtained using secondary ion mass spectrometry (SIMS).

scholarly journals Sazhinite-(La), Na3LaSi6O15(H2O)2, a new mineral from the Aris phonolite, Namibia: Description and crystal structure

2006 ◽  
Vol 70 (4) ◽  
pp. 405-418 ◽  
Author(s):  
F. Cámara ◽  
L. Ottolini ◽  
B. Devouard ◽  
L. A. J. Garvie ◽  
F. C. Hawthorne
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Polarized Light ◽  
Total Content ◽  
New Mineral ◽  
Formula Unit ◽  
X Ray Diffraction ◽  
Average Composition ◽  
Mohs Hardness ◽  
Silicate Layers ◽  
Secondary Ion

AbstractSazhinite-(La) is a new mineral from the Aris phonolite, Windhoek, Namibia. It occurs in vesicles within the phonolite, together with other species crystallized from late-stage hydrothermal fluids: natrolite, aegirine, microcline, apophyllite, sphalerite, analcime, fluorite, villiaumite, hydroxylapatite, galena, makatite, quartz, eudialyte, kanemite, tuperssuatsiaite and korobitsynite. Sazhinite-(La) forms small euhedral crystals up to 1 mm long and 0.4 mm wide, elongated along [001] and flattened on (010), exhibiting the forms {h0l}, {100} and {001}. It has good cleavage parallel to {010} and {001}. Twinning was not observed. Crystals are brittle with a Mohs hardness of 3, creamy white with a white streak, vitreous to pearly lustre, and translucent to transparent. In plane-polarized light, crystals are colourless with a = Z, b = Y, c = X. It is biaxial positive with α = 1.524, β = 1.528, γ = 1.544, all ±0.002, 2Vz(obs) = 46(1)°, and 2Vz(calc.) = 53.6°.Sazhmite-(La) is orthorhombic Pmm2, a = 7.415(2), b = 15.515(3), c = 7.164(1) Å, and V = 824.2 Å3. One crystal was studied by X-ray diffraction, electron microprobe and secondary ion mass spectrometry (SIMS) microanalysis, leading to the average composition (Na2.87K0.02Sr0.01)Σ2.90 [La0.41Ce0.35Pr0.02Nd0.04(Sm,Gd,Dy,Er,Yb)Σ0.01Th0.09U0.01Y0.01Zr0.01Ca0.08Li0.01]Σ1.04 (S15.87S0.06B0.01) (O14.86F0.14).(H2O)2.Weighted full-matrix least-squares refinement on 3369 reflections yielded Rall = 3.8%. The structure is built of corrugated [Si6O15]6- layers linked by [7]-coordinated REE and R4+ cations. This framework leaves channels that contain three [5]- and [6]-coordinated Na cations per formula unit that compensate for the residual charge on the silicate layers. The SIMS analyses confirm a Na content of 3 atoms per formula unit, leading to an ideal formula of Na3LaSi6O15(H2O)2. The third Na atom is bonded to H2O groups and therefore the total content of both Na and H2O may be reduced to 2 and 1 per formula, respectively. The depletion in Na allows for the entrance of high-charge cations such as Th4+.

Evidence for Exchange Between Free and Deep Hydrogen (Deuterium) During Diffusion

1995 ◽  
Vol 377 ◽  
Author(s):  
Howard M. Branz ◽  
Sally Asher ◽  
Yueqin Xu ◽  
Mathieu Kemp
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Emission Rate ◽  
Exchange Process ◽  
Interior Layer ◽  
Exchange Processes ◽  
Hydrogen Deuterium ◽  
The Mean ◽  
Hydrogenated Amorphous ◽  
Secondary Ion ◽  
Tracer Experiments

ABSTRACTWe do not observe any immobile deuterium in secondary ion mass spectrometry D profiles taken after long anneals of hydrogenated amorphous silicon sandwich structures with a thin deuterated interior layer. This suggests that a single deep H level (∼1.4 eV deep) controls H diffusion. On its face, our result contradicts nuclear magnetic resonance and H effusion measurements that show about 30% of H in a-Si:H is “isolated” and deeply bound (∼ 2.1 eV deep). We reconcile our experimental results with the existence of isolated deep H by assuming there is a low-barrier (<< 1.4 eV) exchange process between free H and deep D. In tracer experiments, exchange has the effect of increasing the apparent emission rate of the deep D to nearly that of the shallowest trapped H. We solve for the D profiles and confirm that a deep-trapped D component is consistent with our D tracer profiles if and only if exchange processes are important. We also find that the mean distance D travels before retrapping (100–200Å) is determined by an exchange process of free D with trapped H.

Probing Diffusion Kinetics with Secondary Ion Mass Spectrometry

MRS Bulletin ◽  
2009 ◽  
Vol 34 (12) ◽  
pp. 907-914 ◽  
Author(s):  
Roger A. De Souza ◽  
Manfred Martin
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Transport Processes ◽  
Fast Diffusion ◽  
Diffusion Kinetics ◽  
Analytical Technique ◽  
Self Diffusion ◽  
Solid State Ionics ◽  
Ion Mass Spectrometry ◽  
Secondary Ion

AbstractSecondary ion mass spectrometry (SIMS) is a powerful analytical technique for determining elemental and isotopic distributions in solids. One of its main attractions to researchers in the field of solid-state ionics is its ability to distinguish between isotopes of the same chemical element as a function of position in a solid. With enriched stable isotopes as diffusion sources, this allows self-diffusion kinetics in solids to be studied. In this article, taking oxygen isotope diffusion in oxides as our main example, we present the standard experimental method, and, subsequently, we discuss several promising developments, in particular the opportunities offered by thin-film geometries, and the investigation of inhomogeneous systems, including possible fast diffusion along grain boundaries and making space-charge layers at interfaces “visible.” These examples demonstrate that SIMS is capable of probing mass transport processes over various length scales, ranging from some nanometers to hundreds of micrometers.

Anomalous Diffusion of Hydrogen and the Dependence of the Diffusion Constants on Hydrogen Content in Hydrogenated Amorphous Silicon

1992 ◽  
Vol 258 ◽  
Author(s):  
R. Shinar ◽  
H. Jia ◽  
X.-L. Wu ◽  
J. Shinar
Keyword(s):  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Diffusion Constant ◽  
Relaxation Processes ◽  
Diffusion Constants ◽  
Amorphous Network ◽  
Sputter Deposited ◽  
Hydrogenated Amorphous ◽  
Deposited Film ◽  
Diffusion Of Hydrogen

ABSTRACTThe diffusion constant of hydrogen DH(t) in hydrogenated amorphous silicon (a-Si:H) is strongly dependent on the Si-bonded H content CH of the films. It increases by over four orders of magnitude for CH ranging from 1 to 19 at. %. In an rf sputter-deposited film of CH ∼5 at. % it increases with time at 300 ≤ T ≤ 362°C. The dispersion parameter α in DH(t) = D∞ (ωt)-αis thus negative. This observation and the increase of α with T above a sample-dependent temperature Tτ are discussed in relation to low temperature structural relaxation processes in the amorphous network.

A Multiple Quantum NMR (MQNMR) Study of Hydrogen Microstructure in Boron Doped a-Si:H

1992 ◽  
Vol 258 ◽  
Author(s):  
S. Mitra ◽  
D. H. Levy ◽  
K. K. Gleason ◽  
H. Jia ◽  
J. Shinar
Keyword(s):  
Boron Content ◽  
Secondary Ion Mass Spectrometry ◽  
Multiple Quantum ◽  
Moderate Increase ◽  
Preparation Time ◽  
Boron Doped ◽  
Three Samples ◽  
Secondary Ion ◽  
Weakly Dependent ◽  
Multiple Quantum Nmr

ABSTRACTAn IR and multiple quantum NMR (MQNMR) study of hydrogen microstructure in three boron doped a-Si:H is discussed. The total Si-bonded H content of all films was 6.5 ± 1.0 at.% as determined by the 640 cm-1 IR wagging mode, but their boron content, which was determined by secondary ion mass spectrometry, ranged from 0.02 to 0.3 at. %. The number of correlated hydrogen, as measured at a preparation time of 600 μSwas found to be more weakly dependent on the boron content than previously observed in phosphorous-doped glow-discharge films. Upon annealing at 220 °C the MQNMR spectrum show a moderate increase in the number of correlated hydrogen in all three samples.

Sign in / Sign up

Export Citation Format

Share Document