Electronic Materials Processing Research Articles

Electronic processes in semiconductor materials studied by nanosecond time-resolved microwave conductivity. 1. Cadmium sulfide macroscopic crystal

The transient conductivity resulting from pulsed irradiation (with 3-MeV electrons) of a single, high-resistivity (4 {times} 10{sup 7} {Omega} m) crystal of CdS has been studied by nanosecond time-resolved microwave conductivity. The ratio of the electron-hole pair mobility to the pair formation energy is determined to be 42 {plus minus} 6 {times} 10{sup {minus}4} m{sup 2} V{sup {minus}1} s{sup {minus}1}/eV. For end-of-pulse pair concentrations less than ca. 10{sup 19} m{sup {minus}3}, the half-life of electrons toward localization was 25 ns. With increasing pair concentration above this value, the lifetime was found to become longer. This effect is attributed to trap saturation with the trap concentration estimated to be 3 {times} 10{sup 19} m{sup {minus}3} (5 {times} 10{sup {minus}8} M) with a rate constant toward trapping of 1.1 {times} 10{sup {minus}12} m{sup 3} s{sup {minus}1} (6.6 {times} 10{sup 14} M{sup {minus}1} s{sup {minus}1}). The main trapping site is thought to be the singly ionized sulfur vacancy. No evidence was found for the occurrence of direct electron-hole recombination, and an upper limit of 3 {times} 10{sup {minus}14} m{sup 3} s{sup {minus}1} (ca. 2 {times} 10{sup 13} M{sup {minus}1} s{sup {minus}1}) could be placed on the second-order rate constant for this process.

Sol–Gel Coating of Powders for Processing Electronic Ceramics

A new technique (sol‐gel coating of powders) was utilized to process electronic ceramics such as Sb‐doped SnO2 and positive‐temperature‐coefficient‐of‐resistance (PTCR) BaTiO3 thermistors. Sol‐gel coatings resulted in the densification via a liquid phase of Sb‐doped SnO2 powders. PTCR thermistors were developed from BaTiO3 powders coated by a sol‐gel composition containing dopants (Y), counterdopants (Mn, F), and additives (Si) with uniform microstructures and improved properties. Incorporation of F via the sol‐gel coating increased the reliability of PTCR devices, making them less sensitive to reducing environments. This process may be extended to the processing of other electronic materials.

New Perspectives of Silicon Carbide: An Overview, with Special Emphasis on Noise and Space-Charge-Limited Flow

Silicon carbide single crystals were studied at the University of Florida as part of a large program on ultrastructure processing and environmental stability of advanced structural and electronic materials. We are well aware of the fact that we are one of the few research groups who have pursued interest in this material. Although initially there was much interest in this material, in particular since it is a high band gap, high temperature, inert and chemically stable material (see e.g. 1 ), research on this material slackened considerably from 1960-1 980. The reasons for this are discussed well by Campbell (2). First, as he indicates, in the late 1960s there was a decline in corporate and government research and development funding. At that time, SiC had not carved out its niche in the semiconductor device market, like Si and GaAs. Second, there was the disappearance of the small market in which SiC could have made an impact, such as in space missions to Venus or other hostile atmospheres. Third, the fabrication techniques for SiC were, and are, beset with difficulties, and the hope for cheap devices is, even now, nil. At the end of his article, Campbell expresses only gloom; the enthusiasm of those who were involved in the material development of SiC is over since no viable markets are in sight. Yet, hardly a few years after (or even simultaneously with) Campbell's article, new

Applications of in situ SIMS during processing of electronic materials

AbstractAn in situ SIMS system is described that is capable of providing accurate and reliable control in determining the termination of processes whilst etching through multi‐layer structures. The instrumentation is described and how progressive alterations have been implemented to improve the sensitivity. Various applications are described which show the wide range of material systems that have already been addressed.

Editor chosen for new ACS materials journal

Chemistry professor Leonard V. Interrante of Rensselaer Polytechnic Institute has been selected to be the first editor of the American Chemical Society's newest journal, Chemistry of Materials . The bimonthly journal will cover fundamental research with a molecular level perspective at the interface of chemistry, chemical engineering, and materials science. The journal was approved by the ACS Board at the national meeting in Denver a year ago, and its premier issue is scheduled for January 1989. Interrante expects that chemists working in a variety of areas such as solid-state chemistry and polymer science will be the major contributors to Chemistry of Materials . The journal will give them, as well as chemical engineers and materials scientists, a forum for presenting investigations of the synthesis and properties of solid-state materials, polymeric solids and thin films, and the preparation and chemical processing of electronic and optical materials and devices. This journal will emphasize the chemistr...

Advances in vacuum contamination control for electronic materials processing

The demand for devices with improved performance and yield and fabricated with reduced processing costs is driving advances in electronic materials processing. A most important consideration is the reduction of defects resulting from particulate contamination during processing. Since many of the steps in device processing use vacuum equipment, their requirements are shaping the design of new tools. In this paper we describe the sources of contamination during processing, the techniques used for their reduction, and note vacuum issues that relate to the use of new processing technologies.

Spray Pyrolysis Processing of Optoelectronic Materials

The processing of thin-film semiconducting, optical, and electronic materials by spray pyrolysis processing is reviewed. The major processing parameters, equipment, and chemical solutions utilized in the deposition of sulfides, selenides, oxides, and ternary semiconducting compounds are described in relation to the potential applications of these materials. The prospects of spray pyrolysis processing in photovoltaic, ir optical, and electronic materials technologies and ceramic powder preparation are discussed.

Micro-reaction engineering applications of reaction engineering to processing of electronic and photonic materials

Processing of electronic materials for electronic and opto-electronic devices combines a facinating variety of physical transport processes and chemical reactions that raise new challenges to chemical reaction engineering. These are reviewed along with recent examples of applications of chemical reaction engineering to microelectronic processing. Chemical vapor deposition and plasma processing of thin films are emphasized as areas where chemical reaction engineering could have a significant impact. Other thin film processes, e.g. physical vapor deposition and oxidation, are surveyed briefly. Bulk crystal growth analysis is included to demonstrate recent advances in detailed modelling of physical transport processes of interest to reactor modelling. Finally, common challenges, including micro/macroscopic modelling, large scale computing and fundamental physicochemical phenomena are discussed.

NRC Reviews Surface Processing of Electronic Materials in the United States and Japan

NRC Reviews Surface Processing of Electronic Materials in the United States and Japan

ON ELECTRONIC TRANSPORT PROCESSES IN METALLIC SUPERLATTICES

The electronic transport processes in metallic superlattices are studied by solving Boltzmann's equation with inclusion of a temperature gradient as well as an external magnetic field and by adopting the treatment of interface scattering processes in our revious interpretation of electric conduction characteristics. Variations with modulation wavelength of the thermoelectric power, the electronic thermal conductivity, the Thomson and Hall coefficients are derived for Nb/Ti superlattices. Further experimental investigations on the transport properties of metallic superlattices are expected to help the understanding of the electronic processes in such artificial materials.

Surface morphology of Si(100), GaAs(100) and InP(100) following O 2+ and Cs + ion bombardment

Low energy ion bombardment is an important technique in the processing and analysis of electronic materials. Inert gas and reactive ions are used as the primary excitation agent in Secondary Ion Mass Spectrometry (SIMS) to obtain the depth distribution of dopants and contaminants in semiconductors. Ion etching is also used for pattern delineation in the fabriatiion of devices in the electronics and telecommunications industries. Although the technique is becoming increasingly important, ion erosion of surfaces does not always proceed uniformly and artefacts such as pits, pyramids, cones, facets and other ion-induced topographies are frequently observed. In this paper a systematic study of the effects of 5.5 keV ion bombardment on clean well-characterized surfaces of some important electronic materials (Si(100), Cr-doped semi-insulating GaAs(100) and Fe doped InP(100)) is reported using O 2 2 and Cs + primary ion species. Relatively high doses of10 19 ions cm −2 and 10 20 ions cm −2 have been used to ensure that the observed features are properly developed. Detailed studies of the morphologies have been made using scanning electron microscopy. The implications of the work for SIMS and the integrity of concentration-depth profiles are discussed.

An Overview of Plasma Processing

ABSTRACTAn overview is presented of the plasma processing of materials. The principal components of this overview include the definition and classification of plasmas of interest in materials processing, the methods of plasma generation and the basic engineering principles that govern plasma phenomena. Here emphasis is placed on both plasma theory and on the experimental verification of the models. This is followed by a brief description of principal plasma applications, including thermal plasmas used in melting, refining, plasma deposition and plasma synthesis and low pressure plasmas used in synthesis and in the processing of electronic materials.The review is concluded by a brief discussion of future prospects for plasma technology, where the main developments envisioned are in the area of improved coatings, the processing of electronic materials, melting and refining of refractory metals and superalloys and finally the possibility of more widespread use for plasma systems in extractive metallurgy.

The International Series of Monographs on Physics: Electronic Processes in Non-Crystalline Materials (2nd edn)

N F Mott and E A Davis 1979 Clarendon Press: Oxford University Press xiv + 590 pp price £29 In the seven years since the appearance of the first edition of this book there have been considerable advances in its subject matter. The authors are to be congratulated on producing a second edition that has been considerably rewritten and expanded and still retains the essential ingredients that made the earlier edition so successful.

Semiconductors

Electronic Processes in Non-crystalline Materials. By N. F. Mott and E. A. Davis. Pp. xiii + 437. (Clarendon: Oxford; Oxford University: London, December 1971.) £7.50.

Electronic processes in materials

Electronic processes in materials

Electronic processes in materials

Electronic processes in materials