A Review of Quantum Confinement in Nanocrystalline Silicon in an Oxide Matrix
Aps Meeting Abstracts, Mar 1, 1996
Over the past four years we have generated several publications (D.= W. Boeringer and R. Tsu, Phy... more Over the past four years we have generated several publications (D.= W. Boeringer and R. Tsu, Phys. Rev. B 51, 13337(1995).)on the tunneling current through a diode structure consisting of nanoscale silicon particles (=89 5 n= m) embedded in an oxide matrix. The thickness of this active region is= typically 15 nm. Multiple conduction peaks are usually observed. The multiplicity has bee= n satisfactorily modeled by a particle size distribution with variation usuall= y less than 1 %. Subsequently we have found that "similar conductance peak" showed up in a diode with only a thin oxide, approximately 4 nm. Major differences are: The conductance peaks are broader and less distinct, instead of those wi= th only 10 meV linewidth for the case with Si nanoparticles. (2) Observation of typical conductance peaks near zero bias due to oxide/Si interface defects. (Such structures were usually absent on samples with Si nanoparticles.) (3) At voltages in excess of -30 V on the wafer instead of the -10 to -12 Volts. We conclude that the conductance peak with thin oxide is due to localized defects.
Effects of Light on the Resonant Tunneling in Silicon Quantum Dot Diode
MRS Proceedings, 1995
The resonant tunneling via nanoscale silicon particles embedded in an a-SiO2 matrix in a diode st... more The resonant tunneling via nanoscale silicon particles embedded in an a-SiO2 matrix in a diode structure has revealed a range of intriguing observations such as extremely sharp peaks and steps and periodic oscillations in (conductance-voltage) G-V measurements. Recently we have discovered a drastic sharpening of the conductance peak with light. Phase measurements show that the effects of light may be understood by invoking the filling of charged traps.
Due to the discreteness of electronic charges in a nanoscale system, capacitance is defined in te... more Due to the discreteness of electronic charges in a nanoscale system, capacitance is defined in terms of the total interaction energy of N-electrons confined in a dielectric sphere. Specifically, the distribution of N-electrons is obtained from minimization of the total Coulomb and polarization interaction energy and the formation energy, the work done on the system. Our discrete charge dielectric (DCD) model gives rise to an electrostatic capacitance agreeing with the N ¼ 1 and N cases. For nanometer-size devices, the Schrö dinger equation should be used; however, for size greater than 10 nm, the Poisson equation accounts for spatial symmetry properties resulting from the discrete nature of interacting electrons. Without metallic components, the equal potential landscape does not coincide with our spherical boundary except for the N ¼ 1 case. There is a special configuration associated with each N. Hence, the capacitance defined is monophasic, representing a single electrostatic phase. The most important application of this work may lie in optoelectronics and biological systems.
Because of the presence of phonons, impurities and other defects such as structural disorder, a m... more Because of the presence of phonons, impurities and other defects such as structural disorder, a mean free path L must be introduced in dealing with quantum well structures and superlattices particularly important when amorphous materials are involved. The major effects involved the broadening and level shift of the mini-band states. For crystalline materials, level shift is negligible in comparison to level broadening, however, for amorphous materials, the opposite is true due to the extremely small L.
Si/C superlattice useful for semiconductor devices
Studies of Silicon Nanocrystals
ABSTRACT
A New Type of Silicon Superlattice: Hetero-Epilattice
Abstract : This paper introduces a new type of superlattice, consisting of a semiconductor such a... more Abstract : This paper introduces a new type of superlattice, consisting of a semiconductor such as silicon sandwiched between adsorbed oxygen atoms. Compared to heterojunction quantum structures, this type of superlattice allows a wider variety of man-made solid because of tolerance to interfacial strain. Experimentally, Si/O superlattice is epitaxial with defect density below 10(exp 9)/sq cm. A 9-period structure shows electroluminescence with a peak at 2.2eV, and an effective barrier height of more than 0.5eV. Early on in this project, HRTEM has been exclusively used to demonstrate the epitaxy beyond the monolayer of oxygen introduced. A year ago, superlattice structure in the strain pattern demonstrated the extent of the interfacial strain, being at least four lattice dimension. This is a very important finding because researchers may now use the Semiconductor-Atomic Superlattice (SAS) as a matching section for the epitaxial growth of one with large strain onto the other. A frequently asked question is as follows: Do the oxygen atoms cover the entire 1 x 2 site? If not, is there staggering present? Unfortunately, the answers to these questions may require in-situ STM probing, which may be something for future consideration. Technologically, this research opens the door for future 3D ICs. A list of 17 publications related to this research is included. (10 figures, 17 refs.)
The Role of Covalent and Metallic Radii in Covalent Metallic Superlattices and Two-Dimensional Isoelectronic Alloys
MRS Proceedings, 1987
ABSTRACTCovalent metallic superlattices and isoelectronic alloys consist of ordered layers of, fo... more ABSTRACTCovalent metallic superlattices and isoelectronic alloys consist of ordered layers of, for example, Si/AlP, Ge/GaAs, and Si/Sb,etc. Depending on design, wide range of electrical properties can result. The covalent, metallic and ionic radii play a crucial role in the stoichiometry of epitaxial systems.
Stark quantization in superlattices
Physical Review B, 1991
Title: Stark quantization in superlattices. Authors: Tsu, Raphael; Esaki, L. Affiliation: AA(Univ... more Title: Stark quantization in superlattices. Authors: Tsu, Raphael; Esaki, L. Affiliation: AA(University of North Carolina at Charlotte, Charlotte, North Carolina 28223) AB(IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598). ...
Photoconductivity in Disordered Nickel-Oxide Films
Semiconductor superlattices consisting of alternating layers of two semiconductors with different... more Semiconductor superlattices consisting of alternating layers of two semiconductors with different energy bands were conceived by Esaki and Tsu more than 37 years ago at the IBM Research. It was recognized that such structures would show negative differential conductance, the main device ingredient in amplifier and oscillator, called by us, the Bloch oscillator. Two patents were applied at the very beginning and issued. The concept, due to the availability of molecular beam epitaxy, MBE, particularly developed for GaAs injunction lasers, became reality in a few years, led to the wide spread of 2D systems, eventually led the way for the opening of nanoscience. I used this opportunity to tell the story how it all happened, as an example that progress in science and technology frequently depends on something quite obvious once became known.
Title: Stark quantization in superlattices. Authors: Tsu, Raphael; Esaki, L. Affiliation: AA(Univ... more Title: Stark quantization in superlattices. Authors: Tsu, Raphael; Esaki, L. Affiliation: AA(University of North Carolina at Charlotte, Charlotte, North Carolina 28223) AB(IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598). ...
Uploads
Papers by Raphael Tsu