scholarly journals Synthesis, Optical Properties, and Microstructure of Semiconductor Nanocrystals Formed by Ion Implantation

1996 ◽  
Vol 452 ◽  
Author(s):  
J. D. Budai ◽  
C. W. White ◽  
S. P. Withrow ◽  
R. A. Zuhr ◽  
J. G. Zhu
Keyword(s):  
Optical Properties ◽  
Ion Implantation ◽  
Lattice Structure ◽  
Semiconductor Nanocrystals ◽  
Surface Region ◽  
Substrate Material ◽  
Fused Silica ◽  
High Dose ◽  
Si Substrates ◽  
Nanostructured Composite

AbstractHigh-dose ion implantation, followed by annealing, has been shown to provide a versatile technique for creating semiconductor nanocrystals encapsulated in the surface region of a substrate material. We have successfully formed nanocrystalline precipitates from groups IV (Si, Ge, SiGe), III-V (GaAs, InAs, GaP, InP, GaN), and II-VI (CdS, CdSe, CdSxSe1x, CdTe, ZnS, ZnSe) in fused silica, Al2O3 and Si substrates. Representative examples will be presented in order to illustrate the synthesis, microstructure, and optical properties of the nanostructured composite systems. The optical spectra reveal blue-shifts in good agreement with theoretical estimates of size-dependent quantum-confinement energies of electrons and holes. When formed in crystalline substrates, the nanocrystal lattice structure and orientation can be reproducibly controlled by adjusting the implantation conditions.

Analysis of High Dose Implanted Silicon by High Depth Resolution Rbs and Spectroscopic Ellipsometry and TEM

1984 ◽  
Vol 35 ◽  
Author(s):  
T. Lohner ◽  
G. Mezey ◽  
M. Fried ◽  
L. GhiţA ◽  
C. Ghiţa ◽  
...  
Keyword(s):  
Optical Properties ◽  
Ion Implantation ◽  
Spectroscopic Ellipsometry ◽  
Composite Structures ◽  
Depth Resolution ◽  
High Dose ◽  
Detailed Characterization ◽  
High Depth ◽  
Qualitative Picture

ABSTRACTOne of the applications of high dose ion implantation is to form surface alloys or compound layers. The detailed characterization of such composite structures is of great importance. This paper tries to answer the question: how can we outline, at least, a qualitative picture from the optical properties measured by ellipsometry of high dose Al and Sb implanted silicon. Attempts are done to separate the effect of implanted impurities from the dominant disorder contribution to the measured optical properties. As the ellipsometry does not provide information enough to decide the applicability of optical models therefore methods sensitive to the structure (channeling and TEM) were applied too.

Physical and optical properties of Cu nanoclusters fabricated by ion implantation in fused silica

1994 ◽  
Vol 76 (2) ◽  
pp. 708-715 ◽  
Author(s):  
R. H. Magruder ◽  
R. F. Haglund ◽  
L. Yang ◽  
J. E. Wittig ◽  
R. A. Zuhr
Keyword(s):  
Optical Properties ◽  
Ion Implantation ◽  
Fused Silica ◽  
Cu Nanoclusters

Some optical properties of waveguides made by high energy ion implantation in fused silica

1992 ◽  
Author(s):  
J. Albert ◽  
B. Malo ◽  
D. C. Johnson ◽  
K. O. Hill ◽  
J. L. Brebner ◽  
...  
Keyword(s):  
Optical Properties ◽  
Ion Implantation ◽  
High Energy ◽  
Fused Silica

Radiation Effects in Nonmetals: Amorphization, Phase Decomposition, and Nanoparticles

1998 ◽  
Vol 540 ◽  
Author(s):  
A. Meldrum ◽  
L.A. Boatner ◽  
C.W. White ◽  
D.O. Henderson
Keyword(s):  
Ion Implantation ◽  
Electron Irradiation ◽  
Radiation Effects ◽  
Elevated Temperatures ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Semiconductor Nanocrystals ◽  
Heavy Ion ◽  
Fused Silica ◽  
Near Surface

AbstractRadiation effects in nonmetals have been studied for well over a century by geologists, mineralogists, physicists, and materials scientists. The present work focuses on recent results of investigations of the ion-beam-induced amorphization of the ABO4 compounds – including the orthophosphates (LnPO4; Ln = lanthanides) and the orthosilicates: zircon (ZrSiO4), hafnon (HfSiO4), and thorite (ThSiO4). In the case of the orthosilicates, heavy-ion irradiation at elevated temperatures causes the precipitation of a nanocrystalline metal oxide. Electron irradiation effects in these amorphized insulating ceramics can produce localized recrystallization on a nanometer scale. Similar electron irradiation techniques were used to nucleate monodispersed compound semiconductor nanocrystals formed by ion implantation of the elemental components into fused silica. Methods for the formation of novel structural relationships between embedded nanocrystals and their hosts have been developed and the results presented here demonstrate the general flexibility of ion implantation and irradiation techniques for producing unique near-surface microstructures in ion-implanted host materials.

Microstructure and Size Distribution of Compound Semiconductor Nanocrystals Synthesized by Ion Implantation

1998 ◽  
Vol 536 ◽  
Author(s):  
A. Meldrum ◽  
S. P. Withrow ◽  
R. A. Zuhr ◽  
C. W. White ◽  
L. A. Boatnerl ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Semiconductor Nanocrystals ◽  
Compound Semiconductor ◽  
Fused Silica ◽  
Silica Matrix ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Host Materials ◽  
Device Applications ◽  
Versatile Technique

AbstractIon implantation is a versatile technique by which compound semiconductor nanocrystals may be synthesized in a wide variety of host materials. The component elements that form the compound of interest are implanted sequentially into the host, and nanocrystalline precipitates then form during thermal annealing. Using this technique, we have synthesized compound semiconductor nanocrystal precipitates of ZnS, CdS, PbS, and CdSe in a fused silica matrix. The resulting microstructures and size distributions were investigated by cross-sectional transmission electron microscopy. Several unusual microstructures were observed, including a band of relatively large nanocrystals at the end of the implant profile for ZnS and CdSe, polycrystalline agglomerates of a new phase such as γ-Zn 2SiO4, and the formation of central voids inside CdS nanocrystals. While each of these microstructures is of fundamental interest, such structures are generally not desirable for potential device applications for which a uniform, monodispersed array of nanocrystals is required. Methods were investigated by which these unusual microstructures could be eliminated.

Formation of Au-nanocrystals in TiO2 and SrTiO3 by ion implantation in restricted volumes

2003 ◽  
Vol 792 ◽  
Author(s):  
R. Fromknecht ◽  
G. Linker ◽  
K. Sun ◽  
S. Zhu ◽  
L.M. Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Ion Implantation ◽  
Dose Rate ◽  
Size Distribution ◽  
Average Particle Size ◽  
Surface Region ◽  
High Dose ◽  
Average Particle ◽  
Tem Analysis ◽  
Near Surface

ABSTRACTAu-ions were implanted at RT conventionally and through a mask into TiO2- and SrTiO3-single crystals with doses in the range from 1×1015Au+/cm2 to 1×1017Au+/cm2, and dose rates of ∼1011ions/sec and ∼3×1013ions/sec, at an energy of 260keV; some samples subsequently were annealed at temperatures up to 1100K. The Au-atoms precipitated to nanocrystals during implantation with an average particle size of 1.5nm. HRTEM investigations revealed that the Au-nanocrystals, embedded in amorphous TiO2-regions, have a broad size distribution varying from large sizes in the near surface region to smaller sizes at larger depths. In the annealing process a coarsening and a reorientation of the Au-nanocrystals is observed. At 1000K the particle size of the textured Au-implant was evaluated to be ∼6nm. Implantation with a high dose rate performed through a metal mask with holes of 120μm diameter and without annealing resulted in an almost equidistant arrangement of the Au-nanocrystals with a narrow size distribution of 2–6nm in TiO2 and 3–5nm in SrTiO3 in the near surface region. Au-ion implantation through an e-beam resist mask (50nm × 50nm holes), with doses ranging from 1×1015Au+/cm2 to 4×1015Au+/cm2 at the low dose rate and annealed at 1000K, lead to a periodic structure of the Au-nanocrystals. The nanocrystal size, evaluated from TEM analysis, in the as-implanted state was ∼5nm and after annealing at 1000K sizes of several nanometers to several tens of nanometers were observed.

Structural Stability and Optical Properties of hexagonal and cubic CdSe Nanocrystals synthesized in MgO

2004 ◽  
Vol 848 ◽  
Author(s):  
S.W.H. Eijt ◽  
van Huis ◽  
P.E. Mijnarends ◽  
B.J. Kooi ◽  
M. Nanu
Keyword(s):  
Optical Properties ◽  
Ion Implantation ◽  
Band Gap ◽  
Structural Changes ◽  
Optical Absorption Spectroscopy ◽  
Cdse Nanocrystals ◽  
High Dose ◽  
Electronic Band ◽  
Supersaturated Solid Solutions ◽  
Direct Band

ABSTRACTWe present a study of CdSe nanocrystals synthesized in MgO by precipitation of Cd and Se supersaturated solid solutions, created in MgO single crystals by ion implantation, in the temperature range between 300 °C and 1100 °C. For high-dose ion implantation, optical absorption spectroscopy revealed the presence of the ∼1.8 eV CdSe semiconductor band-edge. Small sized nanocrystals adopt the rocksalt instead of the wurtzite structure because the former fits better in the MgO matrix and results in lower interface energies. A better understanding of these structural changes and optical properties is obtained from ab-initio total energy calculations on wurtzite, zincblende and rocksalt CdSe using the VASP pseudopotential code. The calculated electronic band structures are compared of zincblende CdSe, a direct band-gap semiconductor, and rocksalt CdSe, which has an indirect optical band-gap.

scholarly journals Synthesis, optical properties, and microstructure of semiconductor nanocrystals formed by ion implantation

1996 ◽  
Author(s):  
J.D. Budai ◽  
C.W. White ◽  
S.P. Withrow ◽  
R.A. Zuhr ◽  
J.G. Zhu
Keyword(s):  
Optical Properties ◽  
Ion Implantation ◽  
Semiconductor Nanocrystals

Optical Properties Of Si Nanocrystals Formed In Si02 By Ion Implantation

1998 ◽  
Vol 507 ◽  
Author(s):  
C. W. White ◽  
S. P. Withrow ◽  
A. Meldrum ◽  
J. D. Budai ◽  
D. M. Hembree ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Ion Implantation ◽  
Quantum Confinement ◽  
Dose Dependence ◽  
Interface States ◽  
High Dose ◽  
Size Dependent ◽  
Si Nanocrystals

ABSTRACTSi nanocrystals formed in SiO2 by high-dose ion implantation and annealing give rise to strong optical absorption and intense photoluminescence (PL). The dose dependence of optical absorption provides evidence for size-dependent quantum confinement in the Si nanocrystals. PL peak energies are nearly independent of dose suggesting that surface or interface states play an important role in PL. Estimates of absorption bandgaps in the nanocrystals are given.

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