Junction devices

Semiconductors are materials that are characterized by resistivities iatermediate between those of metals and of iasulators. The study of organic semiconductors has grown from research on conductivity mechanisms and stmcture—property relationships ia soHds to iaclude appHcations-based research on working semiconductor junction devices. Organic materials are now used ia transistors, photochromic devices, and commercially viable light-emitting diodes, and the utility of organic semiconductors continues to iacrease. 

Amorphous Silicon. Amorphous alloys made of thin films of hydrogenated siUcon (a-Si H) are an alternative to crystalline siUcon devices. Amorphous siUcon ahoy devices have demonstrated smah-area laboratory device efficiencies above 13%, but a-Si H materials exhibit an inherent dynamic effect cahed the Staebler-Wronski effect in which electron—hole recombination, via photogeneration or junction currents, creates electricahy active defects that reduce the light-to-electricity efficiency of a-Si H devices. Quasi-steady-state efficiencies are typicahy reached outdoors after a few weeks of exposure as photoinduced defect generation is balanced by thermally activated defect annihilation. Commercial single-junction devices have initial efficiencies of ca 7.5%, photoinduced losses of ca 20 rel %, and stabilized efficiencies of ca 6%. These stabilized efficiencies are approximately half those of commercial crystalline shicon PV modules. In the future, initial module efficiencies up to 12.5% and photoinduced losses of ca 10 rel % are projected, suggesting stabilized module aperture-area efficiencies above 11%. 

One idea to realize a pin junction with conjugated polymers is to create it in situ by electrochemical doping. By using the conjugated polymer in a solid slate electrochemical cell, the production of bipolar light-emitting pin junction devices can be realized [69, 70]. 

Delonno E, Tseng HR, Harvey DD, Stoddard JF, Heat JR (2006) Infrared spectroscopic characterization of [2]rotaxane molecular switch tunnel junction devices. J Phys Chem B 110 7609-7612... 

Robert B. Campbell and Hung-Chi Chang, Silicon Carbide Junction Devices R.E. Enstrom, H. Kressel, and L. Krassner, High-Temperature Power Rectifiers of GaAs P,... 

P.G. LeComber, A.E. Owen, W.E. Spear, J. Hajto, and W.K. Choi, Electronic Switching in Amorphous Silicon Junction Devices... 

Narasimhan, M. Hagler, M. Cammarata, V. Thakur, M. 1998. Junction devices based on sulfonated polyaniline. Appl. Phys. Lett. 72 1063-1065. 

Judd-Hunter color difference scale, 7 321 Juglone, in skin coloring products, 7 847 Juglone derivatives, 21 264-265 Juice softening, 23 463 Junctional heart rhythm, 5 107 Junction capacitance, 22 244 Junction devices, 22 180-181 Junction FETs (JFETs), 22 163, 164. See also Field effect transistors (FETs) physics of, 22 241-245, 249 Junction potentials, 9 582 Junctions, stacking, 23 38-39. See also Josephson junctions p-n junction Just-in-Time technique, 21 172 Jute, 11 287, 288, 292, 293. See also China jute... 

While the application of photovoltaic cells has been dominated by solid-state junction devices principally made from silicon, recent work in this field offers the prospect of efficient solar-energy conversion by novel methods. 

A tunneling junction device was used to determine the water structure at the mercury electrode in an aqueous solution of 0.25MHg2 (N03)2 + 0.3M HNO3. It was found that the structure of water domains is the same as that of hexagonal ice. Hydrogen bonding is a dominant, structuredetermining factor in liquid water near the mercury electrode surface. ... 

Blackstock JJ, Stickle WF, Donley CL, Stewart DR, Williams RS (2007) Internal structure of a molecular junction device chemical reduction of Pt02 by Ti evaporation onto an interceding organic monolayer. J Phys Chem C 111 16-20... 

Nakshima et al. have fabricated p-n junction devices by employing A1 implantation to yield a p-doped layer in n-type 6H-SiC [66]. A Pt layer on top of the p-type ohmic contact (PtSi) provided both protection and a catalytic metal contact to create a chemical gas sensor device. A response (30 and 60 mV, respectively) was obtained to both 50 ppm and 100 ppm of ammonia in nitrogen at 500°C. 

Another p-n junction-based hydrogen sensor has been produced by implanting palladium ions into 6H n-type SiC material [67]. Gold-plated copper contacted the p-n junction device. The gas response was measured as (small) changes in current as the gas ambient was varied between air and 4% in argon in the temperature range 23-240°C. For an absolute voltage above 1.2V, the p-n junction broke down. 

Another type of semiconductor junction device is a transistor, which is capable of two primary types of functions. The first is to amplify an electrical signal. The second is to serve as a switching device for the processing and storage of information. We will briefly describe the junction transistor here, and we will defer the description of another type of transistor called a MOSFET to Section 6.1.2.6. 

MOSFETs. A type of semiconductor device that utilizes oxide ceramics is a metal-oxide-semiconductor field-effect transistor, abbreviated as MOSFET. Just like the semiconductor junction devices of Section 6.1.1.6, the MOSFET is composed of n-and / -type semiconductor regions within a single device, as illustrated in Figure 6.36. 

Fig. 3. Scheme for an explanation of the photovoltaic effect in p—n junction devices (see text)... 

The theory underlying their function is imperfectly understood even after almost a century... although the very nature of these units limits them to small power capabilities, the concept of small-signal behavior, in the sense of the term when applied to junction devices, is meaningless, since there is no region of operation wherein equilibrium or theoretical performance is observed. Point-contact devices may therefore be described as sharply nonlinear under all operating conditions. 

Junction devices -compound semiconductorsm [SEMICONDUCTORS - COMPOUNDSEMICONDUCTORS] (Vol21)... 

If neither of these goals can be realized, layered semiconductors may not become useful electrode material in either semiconductor liquid junction or Schottky junction devices. Fortunately, evidence is already being obtained that the negative effects due to steps can be at least temporarily and partially alleviated (35, 36). Future development of chemical methods to inhibit deflection of minority carriers to the edges of steps and to reduce the high recombination rates at steps may open the way for the use of polycrystalline layered chalcogenide semiconductors in solar cell devices. 

Comparisons of experimental I-V characteristics with those predicted by theoretical models (JJ are commonly made to analyze the effects of illumination on semiconductor junction devices. These comparisons have not normally been made for semiconductor-electrolyte (S-E) junctions, most likely due to the lack of suitable theoretical models. 

FIGURE 3.6. (a) Cross-sectional schematics of a silicon wafer with a nanopore etched through a suspended silicon nitride membrance. SAM is formed between sandwiched Au eletrodes in the pore area (circled), (b) I(V) characteristics of a Au-2 -amino-4-ethynylphenyl-4-ethynylphenyl-5 -nitro-1 -benzenethiolate-Au (chemical structure shown below) molecular junction device at 60 K. The peak current density is 50 A/cm2, the NDR is 2400 pQ. cm2, the peak-to-valley ratio is 1030 1. [Adapted from Ref.30 Chen el al., Science 286, 1550-1552 (1999).]... 

Deviating from the primary method for pH, measurements for deriving SSs are carried out in cells, separating the solutions by a diffusion-limiting or liquid junction device. Liquid junction potentials forming as a result cannot be determined directly and vary with the composition of the solution forming the junction and the geometry of the junction device. The uncertainty due to the liquid junction potential can be estimated from independent measurements or from theoretical assumptions. 

The primary and the secondary buffers are separated by a liquid junction device, preferably a glass disk of fine porosity. Under these conditions, the contribution of the liquid junction potential to the cell voltage is very small. The increase in uncertainty is also very small. 

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