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.

TEM study of CdS nanocrystals formed in SiO2 by ion implantation

1996 ◽  
Vol 54 ◽  
pp. 236-237
Author(s):  
Jane G. Zhu ◽  
C. W. White ◽  
J. D. Budai ◽  
S. P. Withrow
Keyword(s):  
Ion Implantation ◽  
Electronic Device ◽  
Semiconductor Nanocrystals ◽  
Optical Nonlinearity ◽  
Silicon Substrates ◽  
Cds Nanocrystals ◽  
Quantum Confinement Effects ◽  
Transmission Electron ◽  
Device Applications ◽  
Ion Profiles

Quantum confinement effects and enhanced optical nonlinearity are expected from II-VI semiconductor nanocrystals, which are important for novel opto-electronic device applications. The ion implantation method has been used in our study to form CdS nanocrystals inside amorphous SiO2. The CdS nanocrystals were studied by transmission electron microscopy (TEM).The samples were implanted (at room temperature) with equal doses (1×1017 ions/cm2) of Cd and S into a SiO2 layer on (100) silicon substrates and then annealed under Ar + 4%H2 ambient at 800°C and 1000°C for 1 h. Implant energies were chosen to overlap the Cd and S ion profiles in the middle of the oxide layer. CdS precipitates are formed during the thermal annealing.The effect of annealing temperatures on the nanocrystals size distributions are revealed in Figs. 1 and 2. The sizes of CdS nanocrystals are in the range of 2 - 11 nm for the sample annealed at 800°C, and in the range of a few to 16 nm for the sample annealed at 1000°C.

Microstructure of GaAs nanocrystals formed inside single crystalline silicon

1996 ◽  
Vol 54 ◽  
pp. 968-969
Author(s):  
Jane G. Zhu ◽  
C. W. White ◽  
J. D. Budai ◽  
M. J. Yacaman ◽  
G. Mondragon
Keyword(s):  
Electronic Device ◽  
Crystalline Silicon ◽  
Semiconductor Nanocrystals ◽  
Implantation Technique ◽  
Single Crystalline Silicon ◽  
Semiconductor Technology ◽  
Cross Sectional ◽  
Si Substrates ◽  
Transmission Electron ◽  
Device Applications

Semiconductor nanocrystals exhibit novel properties that are important for electronic and opto-electronic device applications. Many methods have been developed to synthesize semiconductor nanocrystals. Among them is the ion implantation technique, which is compatible with the semiconductor technology. It has been recently reported that the compound semiconductor GaAs can be formed inside Si by sequential implantation of Ga and As and thermal annealing.In this study, GaAs nanocrystals were formed by sequential implantation of As and Ga, with the same dose of 1 x 1017 cm-2, into (100) Si substrates at 550°C. The implantation energies were chosen so that the Ga and As ions are overlapped over a few hundred nanometers in depth. The samples were then annealed at 1000°C for 1 h in flowing Ar + 4%H2 atmosphere to form GaAs precipitates. Transmission electron microscopy (TEM) has been used to study the microstructures of these samples.The cross-sectional TEM image in Fig. 1 shows the GaAs precipitates formed inside the Si substrateimplanted with As and then Ga.

scholarly journals Ion Beam Synthesis Of Cds, ZnS, And PbS Compound Semiconductor Nanocrystals

1997 ◽  
Vol 504 ◽  
Author(s):  
C. W. White ◽  
J. D. Budai ◽  
A. L. Meldrum ◽  
S. P. Withrow ◽  
R. A. Zuhr ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Thermal Annealing ◽  
Ion Beam ◽  
Semiconductor Nanocrystals ◽  
Compound Semiconductor ◽  
Size Distributions ◽  
Pbs Nanocrystals ◽  
Ion Beam Synthesis ◽  
The Matrix

ABSTRACTSequential ion implantation followed by thermal annealing has been used to form encapsulated CdS, ZnS, and PbS nanocrystals in SiO2 and Al2O3 matrices. In SiO2, nanoparticles are nearly spherical and randomly oriented, and ZnS and PbS nanocrystals exhibit bimodal size distributions. In Al2O3, nanoparticles are facetted and oriented with respect to the matrix. Initial photoluminescence (PL) results are presented.

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.

Effects of Cesium, Iodine and Strontium Ion Implantation on the Microstructure of Cubic Zirconia

2000 ◽  
Vol 663 ◽  
Author(s):  
L.M. Wang ◽  
S. Zhu ◽  
S.X. Wang ◽  
R.C. Ewing
Keyword(s):  
Ion Implantation ◽  
Ion Concentration ◽  
Cross Sectional ◽  
Peak Displacement ◽  
Cubic Zirconia ◽  
Damage Level ◽  
Transmission Electron ◽  
Ion Energies ◽  
Ionic Size

ABSTRACTCesium, iodine and strontium ions have been implanted into yttria-stabilized cubic zirconia (YSZ) to determine the effects of fission product incorporation in YSZ that is considered as an inert nuclear fuel matrix. The ion implantation was conducted at room temperature to 1 × 1021ions/m2 for each ion with ion energies ranging from 70 to 400 keV. The peak displacement damage level and the peak ion concentration in YSZ reached 205-330 dpa and 11-26 at%, respectively. The microstructure of the implanted YSZ was studied by in situ and cross-sectional transmission electron microscopy. In the iodine and strontium implanted samples, a damaged layer with a high density of defect clusters was observed, while in the cesium implanted specimen, the damaged layer is amorphous. Nanocrystalline precipitates were observed in the strontium implanted specimen after annealing at 1000°C. The results are discussedin terms of the ionic size, mobility and the solubility of the implanted species in YSZ.

Residual Ion Implantation Damage at Source/Drain Junctions of Excimer Laser Annealed Polycrystalline Silicon Thin Film Transistor

2002 ◽  
Vol 715 ◽  
Author(s):  
Kee-Chan Park ◽  
Jae-Shin Kim ◽  
Woo-Jin Nam ◽  
Min-Koo Han
Keyword(s):  
Thin Film ◽  
Ion Implantation ◽  
Excimer Laser ◽  
Polycrystalline Silicon ◽  
Thin Film Transistor ◽  
Silicon Layer ◽  
Silicon Thin Film ◽  
Cross Sectional ◽  
Implantation Damage ◽  
Transmission Electron

AbstractResidual ion implantation damage at source/drain junctions of excimer laser annealed polycrystalline silicon (poly-Si) thin film transistor (TFT) was investigated by high-resolution transmission electron microscopy (HR-TEM). Cross-sectional TEM observation showed that XeCl excimer laser (λ=308 nm) energy decreased considerably at the source/drain junctions of top-gated poly-Si TFT due to laser beam diffraction at the gate electrode edges and that the silicon layer amorphized by ion implantation, was not completely annealed at the juncions. The HR-TEM observation showed severe lattice disorder at the junctions of poly-Si TFT.

Analysis of epitaxial CoSi2/Si and Si/CoSi2/Si heterostructures

1986 ◽  
Vol 44 ◽  
pp. 730-731
Author(s):  
N. Lewis ◽  
E. L. Hall ◽  
B. D. Hunt ◽  
L. J. Schowalter
Keyword(s):  
Integrated Circuits ◽  
Ohmic Contacts ◽  
Fluorite Structure ◽  
Metal Silicide ◽  
Cross Sectional ◽  
Metal Base ◽  
Substrate Side ◽  
Transmission Electron ◽  
Device Applications

The formation of thin epitaxial metal silicide layers on Si and Si/metal silicide/Si heterostructures has received considerable attention recently for applications as ohmic contacts, permeable and metal base transistors and 3-D integrated circuits. Cobalt disilioide (CoSi2) is promising for these applications because its cubic fluorite structure is similar to that of Si. In addition, the lattice parameters of CoSi2 and Si are reasonably close (-1.2% mismatch at room temperature) making this system attractive for epitaxial growth. The quality of the epitaxial layers is particularly important for device applications. In this paper the microstructures of several CoSi2/Si and Si/CoSi2/Si specimens were investigated using transmission electron microscopy. Planar and cross-sectional samples were prepared. The planar specimens were first mechanically ground from the Si substrate side and then ion-milled in argon.

Epitaxial Thin Films And Heterostrcutures of Various Isotropic Metallic Oxides for Device Applications

1994 ◽  
Vol 341 ◽  
Author(s):  
C. B. Eom ◽  
Julia M. Phillips ◽  
R. J. Cava
Keyword(s):  
Thin Films ◽  
Cuprate Superconductors ◽  
Superconducting Devices ◽  
Epitaxial Thin Films ◽  
Metallic Oxide ◽  
Cross Sectional ◽  
Lattice Match ◽  
Metallic Oxides ◽  
Transmission Electron ◽  
Device Applications

AbstractWe have grown epitaxial thin films of various isotropic metallic oxides such as Sr1-xCaxRuO3 and La8-xSrxCu8O2Oin situ by 90° off-axis sputtering. These metallic oxides are pseudo-cubic perovskites with essentially isotropic properties, which could be ideal normal metals for SNS junctions in superconducting devices and for electrodes in ferroelectric devices. We have fabricated epitaxial ferroelectric heterostructures [SrRuO3/Pb(Zr0. 52 Ti0.4 8) O3 /SrRuO3] employing isotropic metallic oxide (SrRuO3) electrodes on substrates of (100) SrTiO3 and (100) Si with an yttria stabilized zirconia buffer layer. They exhibit superior fatigue characteristics over those made with metal electrodes, showing little degradation over 10 cycles, with a large remnant polarization (27 μC/cm2 ). We have also grown epitaxial superconducting heterostructures (YBa2Cu3O7 / La8-xSrxCu8O2O / YBa2Cu3O7 ) with a copper-oxide-based isotropic metallic oxide (La8-xSrxCu8O20) normal metal barrier. X-ray diffraction and cross-sectional transmission electron microscopy reveal these heterostructures to have high crystalline quality and clean interfaces. This material will facilitate fabrication of ideal SNS Josephson junctions with low boundary resistance due to its excellent chemical compatibility and lattice match with cuprate superconductors and will be useful for determining the source of interface resistance in such heterostructures.

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