Exploratory Device Research Articles

Ironie ist Pflicht: John Barth und John Hawkes Bewusstseinsformen des amerikanischen Gegenwartsromans (review)

Reviewed by: Ironie ist Pflicht. John Barth und John Hawkes—Bewußtseinsformen des amerikanischen Gegenwartsromans Wolfgang Iser Heide Ziegler. Ironie ist Pflicht. John Barth und John Hawkes—Bewußtseinsformen des amerikanischen Gegenwartsromans. Heidelberg: Universitätsverlag C., 1995. 354 pp. “Postmodernism” is so firmly established as a term designating a change in the domain of arts and letters that it appears to be self-explanatory. This, however, is not the case. On the contrary, the term has spawned such a welter of explanations that even the first part of the compound has become ambivalent. Does “post” mean a development of or a reaction against “modernism”? If it is something new, why is it linked to what it has superseded? Small wonder that the term has been lumped under all the various “Postisms” for the purpose of exposing it to ridicule. Even what is current in the domain of arts and letters cannot be equated with the hallmarks of high modernism. To call it postmodernism raises the question whether such a concept—if it is a concept at all—expresses a predicament or is just an old-fashioned way of marking off periods of cultural development from one another. It appears to express a predicament insofar as it tends to indicate what it is not, and it is old-fashioned insofar as a break from what has gone before is conceived as a period in its own right. Why should one stick to the old classification of cultural epochs, if there is to be total liberation from the cultural past? This may be one of the reasons why postmodernism has become a partisan issue, dividing those who maintain that it is nothing but a shift within modernity itself from those who see it as the death knell of modernism. What makes this issue even more controversial is the question whether postmodernism—considered to be a cultural event that exceeds the bounds of culture altogether—is a global or a specifically American phenomenon. Heide Ziegler’s book represents an illuminating intervention into various aspects of the current debate as to how postmodernism is to be conceived. She provides a framework to highlight the salient features of postmodernism and their intimate connections with modernism, as well as the way in which the former gains its profile by revealing what lay dormant in the latter. As indicated by the title of the book—which is a quotation from the German Romantic Friedrich Schlegel—she takes the ironic mode as the overriding concern both of modernism and of its successor. Consequently, modernity and postmodernism [End Page 486] are no longer conceived along antiquated guidelines as period concepts in the development of arts and letters, but rather as different forms of consciousness of which the periods in question are nothing but fields of observation. If irony has been the hallmark of literary and artistic activities since 1800, then the diversified forms of its articulation in literature become an umbrella concept relegating the period concept to something subsidiary. Such a focus has one definitive advantage: it is freed from the awkward necessity of listing the various features by means of which modernism may be separated from what came after. Period concepts, as a rule, are fleshed out by taxonomic inventories—a task which becomes all the more arduous when the period concerned can only lay claim to transcending and yet harking back to what has happened before. The very dependence of postmodernism on what it has separated itself from makes it all the more plausible that it should be conceived as a stage at which, as Ziegler contends, irony bodies forth a different form of consciousness. Friedrich Schlegel’s dictum that irony is obligatory entails on the one hand the dismissal of irony as a rhetorical trope and on the other the commitment of the subject to self-reflection. Thus irony has become the all-pervading mode of writing since 1800, and its shifts and turns distinguish a lingering romanticism from modernity and postmodernism. The periods, then, are only ways of punctuating the variegated course in which irony as an exploratory device brings out an endless self-mirroring of subjectivity which, in what is termed postmodernism, continually undercuts...

Electron-beam lithography for advanced device prototyping: Process tool metrology

Direct write electron-beam lithography is the most flexible technique for sub-0.25 μm imaging in an advanced development environment. The resolution and custom exposure capabilities of electron-beam lithography, as well as the rapid turnaround for new device designs, provide early device/technology feasibility demonstration, learning, and proof-of-concept not easily obtainable with other lithographies. We have used a 50 kV shaped-beam system for advanced complementary metal–oxide–semiconductor (CMOS), bipolar, BiCMOS, and DRAM device prototyping as well as for front-end and back-end process development, metrology standard fabrication, exploratory device fabrication, and x-ray mask fabrication. The high throughput, as compared to vector scan systems, of shaped-beam electron-beam lithography was found to be essential in satisfying the requirements of advanced development programs. The key to success has been a complete understanding and integration of the interaction of the resist process, tool, proximity correction, and metrology at 0.25 μm and below. In this article, we will describe the processes used to obtain minimum dimensions down to 0.1 μm in negative and positive resists with 3σ linewidth variation typically better than 0.025 μm. Accurate and precise scanning electron microscopy metrology will be shown to be critical for process development and inspection of device wafers. In addition, tool set-up techniques and proximity correction for sub-0.25 μm lithography will be discussed. Working room temperature CMOS devices and circuits, with physical gate widths as small as 0.1 μm, have been fabricated using e-beam lithography for the critical gate level and optical lithography for all other levels. A mixed lithography approach was found to be the most effective use of the e-beam, lithography capabilities.

Optimized tight-binding valence bands and heterojunction offsets in strained III-V semiconductors

An optimized nearest-neighbor tight-binding description of valence bands in strained-layer III-V semiconductors is developed and applied to the calculation of valence-band offsets at strained heterojunctions. It is first shown that a single set of universal interatomic matrix elements can be found which, when appropriately scaled for bond length, simultaneously provide near-optimum tight-binding predictions of valence-band uniaxial deformation potentials, trends in photoelectric thresholds, and valence bandwidths for the common III-V compounds. Application of the optimized tight-binding model to the calculation of valence-band offsets at strained heterojunctions is then discussed, and one simple approach is described which combines a fully strain-dependent version of the optimized tight-binding model with Tersoff’s quantum-dipole heterojunction model. Offsets calculated using this combined approach are shown to agree with experimental data better than either strain-dependent natural tight-binding offsets or offsets calculated directly from Tersoff’s model. Finally, convenient quadratic expressions for the composition dependence of light-and heavy-hole valence-band offsets, as calculated using the combined approach, are tabulated for several strained and unstrained ternary-on-binary III-V heterojunctions. The balance between accuracy and simplicity offered by our approach should render it useful for exploratory heterojunction device modeling.

GaAs Vertical pin diode using MeV implantation

Vertical pin diodes were fabricated using MeV Si/S coimplantation and keV Be/P coimplantation into undoped semi-insulating GaAs to obtain buried n+ and surface p+ regions, respectively. An exploratory device with a 500 × 500 μm2 junction area and a 3 μm thick intrinsic region had a break-down voltage of 70 V, reverse leakage current density of 40 μA/cm2 at 20 V, an off-state capacitance of 3.9nF/cm2 and a DC forward resistance of 2.4 Ω at 100 mA.