Electronic Properties of Inorganic and Organic Semiconductors and Their Application to National Security Needs
- PDF / 407,990 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 5 Downloads / 185 Views
Electronic Properties
of Inorganic and Organic Semiconductors and Their Application to National Security Needs
national security needs—including devices such as infrared detectors and sources, gamma-ray detectors, and chemical/ biological sensors—will also be discussed.
Inorganic Semiconductors To date, inorganic materials have been used in most semiconductor applications. The most studied and technologically important inorganic semiconductors have the diamond (e.g., Si) or zinc-blende (e.g., GaAs) crystal structure. Figure 1 shows the zincblende crystal structure and the corresponding Brillouin zone. (The symbols label special symmetry points in the zone.) The structure is based on an fcc lattice with two atoms per unit cell. The diamond crystal structure is the same as the zincblende structure, except that the two atoms in the unit cell are the same for diamond, whereas they are different for zinc blende. The Brillouin zones are the same for the two structures, but for the diamond structure, there is an additional inversion symmetry operator. To understand why these inorganic semiconductors are insufficient for the range of detection methods needed for national se-
Darryl L. Smith Abstract The following article is based on the plenary presentation given by Darryl L. Smith of Los Alamos National Laboratory on December 1, 2003, at the Materials Research Society Fall Meeting in Boston. The presentation contrasted the electronic structure of inorganic semiconductors with that of organic semiconductors, examined how the differences in electronic structure lead to complementary physical properties, and discussed applications of these materials—including infrared detectors and sources, gamma-ray detectors, and chemical/biological sensors—that are of interest to issues of national security. Keywords: electronic structure, inorganic, national security, organic, polymers, semiconductors.
Introduction One of the major issues in national security is the detection of potentially hazardous materials before they do harm to people or property. Thus, the sensing of chemical, biological, and nuclear agents quickly, specifically, and at a distance is of primary importance. Currently available detectors based on semiconductors have a wide range of applicability; high-energy and low-energy ends of the spectrum are especially important. This presentation describes how combinations of inorganic and organic semiconductors might increase our remote sensing ability in these critical energy regions. We contrast the electronic structures of inor-
MRS BULLETIN/SEPTEMBER 2004
ganic semiconductors, such as silicon and gallium arsenide, with organic semiconductors, such as the polymer poly(pphenylene vinylene) (PPV) and the small molecule pentacene. While neither organic nor inorganic semiconductors by themselves have the necessary electronic structure, the differences in that structure between the two classes of materials lead to useful complementary physical properties. Heterostructures containing these materials could provide the crit
Data Loading...
