From San Diego
ACS meeting attracts 14,000 to San Diego The American Chemical Society's 207th national meeting attracted more than 14,000 attendees to San Diego for a wide variety of activities, from presentation of more than 5,700 papers to meetings of ACS governance bodies. Many sessions—especially papers by prominent scientists—drew overflow crowds. For instance, the recipient of the James Flack Norris Award in Physical Organic Chemistry, Harvard University professor George M. Whitesides, attracted a huge crowd to his award address on noncovalent synthesis, delivered to a session of the Division of Organic Chemistry. And the SciMix event, combining chances to socialize and to view more than 225 posters from 14 ACS divisions, drew several thousand attendees. Among governance actions, the ACS Council, in one of its shortest meetings in recent years, voted to keep 1995 member dues at this year's $96 level, and chose candidates for the fall election for 1995 president-elect. The two candidates—Allen J. Bard, Hackerman-Welch Regents Chair, Chemistry, at the University of Texas, Austin; and Ronald C. Breslow, Mitchill Professor of Chemistry at Columbia University, New York— were selected from four nominees. The other two candidates were Daryle H. Busch, Roberts Distinguished Professor at the University of Kansas, Lawrence; and Herbert D. Kaesz, professor of inorganic chemistry at the University of California, Los Angeles. The council also approved a document, "The Chemist's Code of Conduct," outlining ethical standards ACS expects of its members and of chemical professionals in general. It is intended to replace "The Chemists's Creed," approved by the council 25 years ago. And councilors adopted a revised version of the ACS Academic Professional Guidelines, approved in 1991, to reflect concerns expressed by college faculty who teach undergraduates. The board of directors approved 1995 subscription prices for ACS journals and magazines. Member prices will remain at 1994 levels for 12 publications and rise for 10 (up an average of 3.4% for the 22
Almost 250 companies displayed their newest products at the ACS exhibition. publications), reflecting increases in numbers of pages and in frequency of publication. Nonmember subscriptions will rise for all publications except CHEMTECH, up an average of 11%. Both the council and board heard reports about the society's strong financial performance in 1993. ACS operating funds ended the year with an excess of revenues over expenses, before adjustments, of $3.02 million, $511,000 more than budgeted. After all adjustments— including a one-time charge of $13.8 mil-
lion for an accounting change in postretirement benefits for ACS staff—operating fund expenses surpassed revenues by $5.3 million. This is $57 million better than anticipated in the 1993 budget. Also contributing to a successful year was recruitment of a record number— 14,000—of new and reinstated members. The previous high was 12,000 in 1982. Total ACS membership rose to more than 149,000 by year's end—a net gain of about 3,000. Ernest Carpenter
Miles buys ChemDesign, custom chemicals maker Adding to ongoing shifts in the multibillion-dollar custom chemical business (C&EN, Jan. 31, page 26), Miles, the U.S. arm of Bayer A.G., will acquire ChemDesign, an 11-year-old custom fine chemicals producer. Miles will pay about $105 million, including debt assumption of about $24 million, for the Fitchburg, Mass.-based firm. ChemDesign had sales of about $44 million and net earnings of $1.14 million in 1992, the most recent year available. Miles is not a custom chemicals maker, so the acquisition makes sense: Its product lines in agricultural and photographic chemicals, pharmaceuticals, and a wide variety of specialty chemicals are based on the types of chemicals ChemDesign makes. ChemDesign will continue operating under the same name as a Miles subsidiary. ChemDe-
sign's 400 employees and current management will remain in place. "ChemDesign represents a good fit into Miles' long-term business strategy," says Helge H. Wehmeier, Miles president and chief executive officer (CEO). "Its addition to our operations complements our product mix and allows us to bring the results of our worldwide R&D efforts to the marketplace more quickly." The merger will help solidify ChemDesign's position as a North American producer of photoactive compounds for the microelectronics and lithographic industries, says Richard E. T. Brooks, ChemDesign founder, chairman, and CEO. The company will continue to provide custom manufacturing services through operations in Fitchburg and its wholly owned subsidiary in Marinette, Wis., SpecialtyChem Products. In an inMARCH 21,1994 C&EN
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inability to make a gallium arsenide analog of the widely used siliconbased transistor known as a MOSFET (metal-oxide semiconductor field effect transistor). In a MOSFET, current flows from source to drain through a channel in the doped silicon. The current can be turned off by applying a voltage to the "gate" electrode, which is separated from the silicon by an oxide layer (Si02, or silica). Silicon is "nature's perfect semiconductor," Barron remarks, and its naturally occurring oxide is the perfect insulator to go with it. Gallium arsenide, by contrast, doesn't have a native oxide that can be used in the same way. That hasn't stopped scientists from making gallium arsenide-based transistors, however. In fact, these devices, known as MESFETs (metal semiconductor FETs), are used in supercomputers and in some military applications because their switching speed is much faster than that of silicon transistors. However, the absence of an insulating layer between the gate and the semiconductor (GaAs) in MESFETs means that these devices don't switch on and off cleanly, as silicon devices do. "It's like a leaky tap," Barron told the meeting participants. "You have to put five to 12 MESFETs in a row" to get close to a "zero" signal (no current). To circumvent this problem, he says, device architects have had to design some highly complicated circuits. And on top of that, MESFETs consume a lot of power (because "electrons flow into the gate when they're not supposed to," Barron says).
Scientists have long been seeking the ideal insulator that "does everything that silica does for silicon," Barron notes. The insulator would have to be compatible with gallium arsenide and have a similar crystal structure, as well as being electronically inert, chemically stable, etchable, inexpensive, and easy to work with. Because no suitable candidate has thus far been found in nature, Barron and his coworkers methodically set out to create one. What they produced is a new phase of gallium sulfide with a cubic structure that matches gallium arsenide's. The new insulating phase is easily produced using metal-organic From San IHego chemical vapor deposition—the filmgrowth technique currently employed to make GaAs-based devices. Using this vapor technique, films of cubic GaS are deposited by decomposing a cubic precursor, [(fer£-butyl)GaS]4, at about Molecular design and synthesis of a new 400 °G insulating material has allowed scientists Barron and coworkers Phillip P. Jento fabricate a new type of transistor that kins, Andrew N. Machines, and Masshows promise for high-speed, lowsood Tabib-Azar have incorporated this power applications in a new generation cubic GaS layer into a simple prototype of consumer electronics and communiGaAs device that, in a playful mood, cations devices. they named a FETISH (Field Effect TranThe new transistor is based on the sistor with an Insulating Sulfide Heterosemiconductor gallium arsenide (GaAs) junction). The new device, grown under and a new insulator, cubic gallium sulnonoptimized conditions, performs betfide (GaS). The development was anter than a GaAs MESFET but not as well nounced by Andrew R. Barron, a profesas a silicon MOSFET. sor of chemistry at Harvard University who led the research, at a symposium "You're not going to replace all silicon held by the Division of Industrial & Endevices with gallium arsenide tomorrow gineering Chemistry at the American because of [these results]," Barron Chemical Society national meeting. stressed in his ACS talk. That's particularly true because gallium arsenide is Barron believes the new transistor expensive and many devices don't recould extend use of gallium arsenide— quire the higher speeds it makes possiand even improve its performance—in ble. But he believes that replacapplications where, despite some ing currently used MESFETs limitations, it is already being with FETISHs would significantused. Gallium arsenide, he notes, Cubic gallium sulfide insulating ly improve device performance. is the semiconductor of choice for layer is key to new transistor Paul A. Kohl, a chemical engicertain "niche" applications. These 100 urn neering professor who works at include lasers for optical commuE ^ M Georgia Institute of Technology's nications, LEDs (light-emitting Gate (Au/Ge) Microelectronics Research Center diodes) for consumer electronics, Drain (Au/Ge) 5|im Source (Au/Ge) 100 |im ji—H, 100 jim in Atlanta, thinks Barron's tranmicrowave circuits for cellular sistor is "a great first step." But, phones, and circuits used for proCubic GaS he adds, "there's still quite a long cessing huge amounts of data in n-Type GaAs active layer 0.5 jam way to go" before a practical galreal time. lium arsenide technology can be But outside of such specialty realized. 0.8 urn applications, Barron points out, Undoped GaAs buffer layer Barron does not dispute that. In gallium arsenide has not been fact, he's working with Gallia Inc., able to dethrone silicon where Semi-insulating GaAs substrate a Cambridge, Mass.-based microsilicon is king—in digital elecelectronics firm, to commercialize tronics. One reason is gallium the new technology. arsenide's higher cost. But anNote: Dimensions not to scale. Ron Dagani other obstacle has been scientists' dustry where small firms must work hard to comply with a plethora of environmental and safety rules, ChemDesign has been recognized for using innovative technology to control environmental releases. The acquisition, expected to take effect in mid-May, will be carried out through a cash tender offer of $8.50 per share for all 9.4 million ChemDesign shares. On the day the agreement was announced, ChemDesign shares jumped 27% in value, from $6!/2 to $814 per share. Ann Thayer
New transistor class is based on GaS, GaAs
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