Gallium oxide (Ga2O3) is emerging as a viable candidate for certain classes of power electronics, solar blind UV photodetectors, solar cells, and sensors with capabilities beyond existing technologies due to its large bandgap. It is usually reported that there are five different polymorphs of Ga2O3, namely, the monoclinic (β-Ga2O3), rhombohedral (α), defective spinel (γ), cubic (δ), or orthorhombic (e) structures. Of these, the β-polymorph is the stable form under normal conditions and has been the most widely studied and utilized. Since melt growth techniques can be used to grow bulk crystals of β-GaO3, the cost of producing larger area, uniform substrates is potentially lower compared to the vapor growth techniques used to manufacture bulk crystals of GaN and SiC. The performance of technologically important high voltage rectifiers and enhancement-mode Metal-Oxide Field Effect Transistors benefit from the larger critical electric field of β-Ga2O3 relative to either SiC or GaN. However, the absence of clear demonstrations of p-type doping in Ga2O3, which may be a fundamental issue resulting from the band structure, makes it very difficult to simultaneously achieve low turn-on voltages and ultra-high breakdown. The purpose of this review is to summarize recent advances in the growth, processing, and device performance of the most widely studied polymorph, β-Ga2O3. The role of defects and impurities on the transport and optical properties of bulk, epitaxial, and nanostructures material, the difficulty in p-type doping, and the development of processing techniques like etching, contact formation, dielectrics for gate formation, and passivation are discussed. Areas where continued development is needed to fully exploit the properties of Ga2O3 are identified.

A review of Ga2O3 materials, processing, and devices

http://nathan.instras.com/documentDB/paper-69.pdf

Porous silicon: a quantum sponge structure for silicon based optoelectronics

2.3. Ionic Liquids (ILs) 5374 2.4. Complexation Reactions on Oxidized CNTs 5375 2.5. Halogenation 5376 2.6. Cycloaddition Reactions 5377 2.7. Radical Additions 5379 2.8. Nucleophilic Additions 5381 2.9. Electrophilic Additions 5381 2.10. Electrochemical Modifications 5381 2.11. Plasma-Activation 5381 2.12. Mechanochemical Functionalizations 5382 3. Noncovalent Interactions 5382 3.1. Polynuclear Aromatic Compounds 5382 3.2. Interactions with Other Substances 5384 3.3. Interactions with Biomolecules 5385 4. Endohedral Filling 5386 4.1. Encapsulation of Fullerenes 5386 4.2. Encapsulation of Organic Substances 5387 4.3. Encapsulation of Inorganic Substances 5387 5. Decoration of CNTs with Metal Nanoparticles 5388 5.1. Covalent Linkage 5388 5.2. Direct Formation on Defect Sites 5388 5.3. Electroless Deposition 5388 5.4. Electrodeposition 5389 5.5. Chemical Decoration 5390 5.6. Deposition of Nanoparticles onto CNTs 5391 5.7. π-π Stacking and Electrostatic Interactions 5391 6. Concluding Remarks 5392 7. Acknowledgments 5392 8. References 5392

Current progress on the chemical modification of carbon nanotubes.

Recent advances in nonsilica fiber technology have prompted the development of suitable materials for devices operating beyond 155 mu m The III-V ternaries and quaternaries (AlGaIn)(AsSb) lattice matched to GaSb seem to be the obvious choice and have turned out to be promising candidates for high speed electronic and long wavelength photonic devices Consequently, there has been tremendous upthrust in research activities of GaSb-based systems As a matter of fact, this compound has proved to be an interesting material for both basic and applied research At present, GaSb technology is in its infancy and considerable research has to be carried out before it can be employed for large scale device fabrication This article presents an up to date comprehensive account of research carried out hitherto It explores in detail the material aspects of GaSb starting from crystal growth in bulk and epitaxial form, post growth material processing to device feasibility An overview of the lattice, electronic, transport, optical and device related properties is presented Some of the current areas of research and development have been critically reviewed and their significance for both understanding the basic physics as well as for device applications are addressed These include the role of defects and impurities on the structural, optical and electrical properties of the material, various techniques employed for surface and bulk defect passivation and their effect on the device characteristics, development of novel device structures, etc Several avenues where further work is required in order to upgrade this III-V compound for optoelectronic devices are listed It is concluded that the present day knowledge in this material system is sufficient to understand the basic properties and what should be more vigorously pursued is their implementation for device fabrication (C) 1997 American Institute of Physics

The physics and technology of gallium antimonide: An emerging optoelectronic material

Evaluation of mild acid oxidation treatments for MWCNT functionalization

The behavior of silicon slices very heavily implanted (1.5\ifmmode\times\else\texttimes\fi{}${10}^{17}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$) with phosphorus was investigated by transmission electron microscopy and secondary neutral mass spectrometry (SNMS) after annealing at 800, 850, 900, and 1000 \ifmmode^\circ\else\textdegree\fi{}C. Precipitation of large monoclinic, and partially orthorhombic, SiP particles takes place in the most heavily doped region. From the shape of the SNMS profiles in the dissolution stage of these precipitates, we determined the concentration ${\mathit{C}}_{\mathrm{sat}}$ of P in equilibrium with the conjugate phase: ${\mathit{C}}_{\mathrm{sat}}$=2.45\ifmmode\times\else\texttimes\fi{}${10}^{23}$exp(-0.62/kT) ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$. This concentration has to be compared with the equilibrium concentration ${\mathit{n}}_{\mathit{e}}$ of the electrically active dopant. To this end, more accurate determinations of ${\mathit{n}}_{\mathit{e}}$ were performed on heavily P-doped polysilicon films. It was found that ${\mathit{n}}_{\mathit{e}}$=1.3\ifmmode\times\else\texttimes\fi{}${10}^{22}$exp(-0.37/kT) ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$. Hence for T\ensuremath{\gtrsim}750 \ifmmode^\circ\else\textdegree\fi{}C, ${\mathit{C}}_{\mathrm{sat}}$ exceeds ${\mathit{n}}_{\mathit{e}}$ and the concentration (${\mathit{C}}_{\mathrm{sat}}$-${\mathit{n}}_{\mathit{e}}$) of inactive mobile P increases with temperature. The formation and the diffusion behavior of this inactive dopant are in keeping with a preprecipitation phenomenon. \textcopyright{} 1996 The American Physical Society.

Dopant and carrier concentration in Si in equilibrium with monoclinic SiP precipitates

ε-Ga 2 O 3 epilayers as a material for solar-blind UV photodetectors

Engineering interfacial structure in “Giant” PbS/CdS quantum dots for photoelectrochemical solar energy conversion

The precipitation and dissolution of monoclinic SiAs, in Si samples implanted with 1 and 1.5\ifmmode\times\else\texttimes\fi{}${10}^{17}$ ${\mathrm{As}}^{+}$/${\mathrm{cm}}^{2}$, was followed at 800, 900, and 1050 \ifmmode^\circ\else\textdegree\fi{}C by transmission electron microscopy (TEM) and secondary neutral mass spectrometry. It has been found that the concentration ${\mathit{C}}_{\mathrm{sat}}$ of mobile As, which diffuses after equilibration with the monoclinic SiAs precipitates, is given by ${\mathit{C}}_{\mathrm{sat}}$=1.3\ifmmode\times\else\texttimes\fi{}${10}^{23}$ exp(-0.42/kT) ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$, where kT is in eV. This saturation concentration includes different states of As in equilibrium with the monoclinic phase at the annealing temperatures, namely, (i) the electrically active and (ii) the inactive mobile dopant. The results presented in this paper indicate that the inactive As is in the form of clusters. The link between the clustering phenomenon and the presence of small particles detected by TEM observations is also discussed.

Precipitation, aggregation, and diffusion in heavily arsenic-doped silicon.

A Eu III complex, tris-dibenzoylmethane mono-1,10-phenanthroline-europium(III) [Eu(DBM) 3 (Phen)], can be easily adsorbed in situ via hydrophobic interactions to single-walled carbon nanotube (SWNT) surfaces from a methanol solution. The Eu III -containing material has been comprehensively characterized via thermogravimetric analysis (TGA), UV-vis-NIR absorption and luminescence spectroscopy, Raman spectroscopy, atomic force microscopy (AFM), high-resolution transmission electron microscopy (HR-TEM)), Z-contrast scanning transmission electron microscopy (STEM) imaging, and energy dispersive X-ray spectroscopy (EDS). The photophysical investigations revealed that the presence of a SWNT framework does not affect the lanthanide-centered luminescence stemming from the characteristic electronic transitions within the 4f shell of the Eu III ions. Such straightforward synthetic route leads to the preparation of luminescent SWNTs without significantly affecting the electronic and structural properties of the carbon framework, opening new possibilities of designing new classes of CNTs for biomedical applications.

Andrea Parisini

Papers

Dopant and carrier concentration in Si in equilibrium with monoclinic SiP precipitates

ε-Ga 2 O 3 epilayers as a material for solar-blind UV photodetectors

Engineering interfacial structure in “Giant” PbS/CdS quantum dots for photoelectrochemical solar energy conversion

Precipitation, aggregation, and diffusion in heavily arsenic-doped silicon.

Wet Adsorption of a Luminescent EuIII complex on Carbon Nanotubes Sidewalls