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Carrier's Diffusion Under the thermal equilibrium, i.e., in the absence of excess carriers, the carrier recombination is exactly matched by thermal generation of carriers, so that the electron and hole concentrations remain constant in time. is the concentration of carriers in an intrinsic semiconductor. The answer is that the equlibrium minority carrier density is negligibly small compared with the excess minority carrier density. www.mtmi.vu.lt /pfk/funkc_dariniai/sol_st_phys/diffusion_applet.htm   (904 words)

Semiconductor Encyclopedia Articles @ TechnicalStuff.com (Technical Stuff)   (Site not responding. Last check: 2007-10-20) The concentration of carriers in an intrinsic semiconductor is strongly dependent on the temperature. In this case the electrons are the majority carriers and the holes are the minority carriers. It also follows from this that minority carrier concentrations in doped semiconductors are dependent on temperature to the square of the extent that carrier concentrations in intrinsic semiconductors are, since the majority carrier concentration is effectively fixed at the doping level. www.technicalstuff.com /encyclopedia/Semiconductor   (2179 words)

[No title]   (Site not responding. Last check: 2007-10-20) The minority carriers are injected at Emitter junction (e) and are collected at the Collector junction (c). The minority carrier density profile is dependent on the relative magnitude of the Base width, Wb, relative to the diffusion length (Ln or Lp) of the minority carrier in the Base. For a back-to-back PN junction structure to operate as a transistor, it is essential that a substantial fraction of the excess minority carriers, injected by forward bias at one junction, survive the recombination in the Base region and successfully arrive by diffusion at the other junction where they are collected. jas.eng.buffalo.edu /education/bjt/longshort/intro.html   (666 words)

F28-02 Standard Test Methods for Minority-Carrier Lifetime in Bulk Germanium and Silicon by Measurement of ... The minority carrier lifetime is the square of the diffusion length divided by the minority carrier diffusion constant which can be calculated from the drift mobility. SPV measurements are sensitive primarily to the minority carriers; the contribution from majority carriers is minimized by the use of a surface depletion region. In the absence of carrier trapping, both the SPV and PCD methods should yield the same values of lifetime (1) providing that the correct values of absorption coefficient are used for the SPV measurements and that the contributions from surface recombination are properly accounted for in the PCD measurement. www.astm.org /DATABASE.CART/REDLINE_PAGES/F28.htm   (453 words)

NREL: Measurements and Characterization - Minority-Carrier Lifetime Spectroscopy Minority-carrier lifetime spectroscopy is a method to study the recombination processes of materials optically or electronically. It examines the return of photoexcited carriers back to equilibrium as a function of time and provides a measure of the "lifetime" of the excess carriers. This is accomplished with varying levels of volume excitation and sample temperatures of 4 to 300 K. One optical detection technique called time-correlated single-photon counting or time-resolved photoluminescence provides exceptionally fast system response times of 20 ps (optical detection from 0.4 to 1.0 µm) and 100 fs (optical detection from 0.5 to > 2 µm). www.nrel.gov /pv/measurements/minority_carrier.html   (252 words)

Minority carrier lifetime and noise in abrupt molecular-beam epitaxy-grown HgCdTe heterostructures Journal of ... For each measurement temperature, the steady-state excess carrier lifetime determined experimentally was compared to the theoretical bulk lifetime for material with x = 0.32 and effective n-type doping density of 3.7 x 10^sup 14^cm^sup -3^. Alternatively, the reduction in effective lifetime above 180 K may be understood as a "loss" of carriers from the narrow bandgap absorbing layer that are promoted across the potential barrier in the conduction band into a low lifetime, wider bandgap capping layer. The reduction in lifetime as a function of inverse temperature for temperatures above 180 K may be fitted by a "cap lifetime" that has an activation energy equal to the change in bandgap across the heterostucture and scaled by a fitting constant. www.findarticles.com /p/articles/mi_qa3776/is_200307/ai_n9260992   (433 words)

Simplified solar cell material tester - Patent 4656419 From the normalized ratio of the two photovoltages or the two intensities, the minority carrier diffusion length may be determined, given the two wavelengths at which the sample was illuminated, and with other factors being standardized or known. 3, and the minority carrier diffusion length may be displayed or printed out by the display or printer 62 shown associated with the microprocessor 60. When the sample thickness is several times the value of the minority carrier diffusion length, then the surface photovoltage signal amplitude, either peak-to-peak or RMS is given by the following relationship: ##EQU1## where alpha is the semiconductor absorption coefficient at a given wavelength and "L" is the minority carrier diffusion length. www.freepatentsonline.com /4656419.html   (3467 words)

SUBSAFE   (Site not responding. Last check: 2007-10-20) The majority carrier injection stops first and then the minority carrier injection (see Figure 1 right). During the turn-off of the minority carrier injection the reverse recovery current of the parasitic NPN transistor's emitter-base diode leads to a positive potential shift peak (grew color = positive potential above 0.5 V). After that the minority carrier injection starts at the right power transistor and then the majority carrier injection at the left power transistor, whereas the majority carrier injection stops first and then the minority carrier injection. www.iis.ee.ethz.ch /nwp/subsafe/movie/movie3.html   (150 words)

Bipolar Junction Transistors The values of the minority carrier densities at the edges of the depletion regions are indicated on the Figure 5.3.1. The emitter current therefore equals the excess minority carrier charge present in the base region, divided by the time this charge spends in the base. The minority carrier lifetime in the base is 10 ns. ece-www.colorado.edu /~bart/book/book/chapter5/ch5_3.htm   (1583 words)

bjtideal The values of the minority carrier densities at the edges of the depletion regions are indicated on the figure. This relation ship is also referred as the reciprocity relation and can be derived by examining the minority carrier current through the base. Saturation also implies that a large amount of minority carrier charge is accumulated in the base region. physics.ship.edu /~mrc/pfs/308/semicon_book/bjtideal.htm   (1366 words)

Impact of Bulk and Perimeter Recombination on Reverse Recovery of p+n 4H-SiC Diodes In some applications shorter minority carrier lifetimes facilitate fast carrier recombination required to realize high-frequency bipolar device switching, while longer lifetimes that maximize bipolar device current density and gain (at the tradeoff expense of device switching speed) are often desired in lower-frequency applications. Improvement of the minority carrier lifetimes in operational SiC devices is important if SiC bipolar electronics are to be implemented and utilized to their full potential. The effective minority carrier lifetimes were characterized by measuring the reverse recovery switching transient properties of each diode in a minimum inductance test circuit. www.grc.nasa.gov /WWW/SiC/publications/JEMPGN4.98/JEMPaper98.HTML   (4010 words)

[No title]   (Site not responding. Last check: 2007-10-20) The incident laser pulse, very narrow, produces excess minority carrier holes whose concentration profile initially assimilates a delta function, when viewed as a function of position along the sample length. Eq.(1) does not, however, describe the carrier drift motion because its peak remains fixed at x=0, independent of time t, nor it describes the recombination process because the total number of carriers is constant in time in eq.(1). These excess carriers are the signal currents in a photodetector, a pn junction diode, or the bipolar junction transistor. jas.eng.buffalo.edu /education/semicon/diffusion/math.html   (786 words)

MATTER Glossary   (Site not responding. Last check: 2007-10-20) In doped semiconductors which show extrinsic behaviour one carrier, the majority carrier, dominates conductivity. The other type of carrier, which usually has a very much lower carrier density, is the minority carrier. In a p-type material the minority carrier is the electron, while in an n-type material holes are the minority carrier. www.matter.org.uk /glossary/detail.asp?dbid=264   (52 words)

Transistor - Wikipedia, the free encyclopedia 1912–1981), working at Compagnie des Freins et Signaux Westinghouse in Paris, France applied for a patent on an amplifier based on the minority carrier injection process which they called the "transistron." Since Bell Labs did not make a public announcement of the transistor until June 1948, the transistron was considered to be independently developed. It is often less expensive and more effective to use a standard microcontroller and write a computer program to carry out a control function than to design an equivalent mechanical control function. MESFETs are JFETs, in which the reverse biased PN junction is replaced by a semiconductor-metal Schottky-junction. en.wikipedia.org /wiki/Transistor   (3490 words)

Power Analysis Power Analysis designed and developed the system that the airline carrier uses to manage all of their domestic and international properties. This database is used to track all information pertaining to the leases for the airline carrier "On-Airport" and "Off-Airport" properties. The Chicago Minority Business Development Council, Inc. (CMBDC) is a premier organization for increasing business opportunities between major buying organizations and minority-owned businesses. www.poweran.com /projects.htm   (227 words)

Electrochemistry - Institut für Angewandte Physik Although the same number of electrons in the LUMO and holes in the HOMO are produced, the concentration of minority carriers is changed significantly whereas the concentration of majority carriers is basically uneffected [4]. In the given model reaction holes are the minority carrier and their transfer leads to the observed oxidation of the thiol only during illumination of the elctrode. Charging of surface states by light-induced minority carriers is observed in the cathodic overshoot at the beginning of illumination, their discharging by recombination with majority carriers is detected when the beam is blocked again in an anodic overshoot. wwwiap.physik.uni-giessen.de /molmaterials/elchem.htm   (1539 words)

UCF Department of Physics Current research, which is funded by the National Science Foundation, American Chemical Society, and NATO is primarily focused on nano-scale electric field-induced tuning of semiconductor opto-electronic properties and studies of current injection-induced effects and carrier transport in wide band gap semiconductors and devices. Minority carrier transport in p-type Zn0.9Mg0.1O doped with phosphorus Minority carrier transport in GaN and related materials www.physics.ucf.edu /faculty_chernyak.php   (446 words)

Intrepid Sea, Air & Space Museum - The aircraft carrier Intrepid will return home to Pier 86 on Manhattan’s west side on Friday, September 26, 2008 — the birthday of the Museum’s late founder, Zachary Fisher. Intrepid’s 9:00 AM scheduled arrival was followed by an 11:00 AM welcome ceremony. Ceremony participants included Staten Island Borough President, James Molinaro; City Council Minority Leader, James Oddo and United States Coast Guard Commander, Eric Christensen. www.intrepidmuseum.org   (384 words)

Minority Carrier Lifetime in p-HgCdTe Journal of Electronic Materials - Find Articles Over the years, at DRS, we have developed a technology base for both n- and p-type HgCdTe materials parameters that are relevant to photodiode design and fabrication. This paper will discuss data that we have taken recently on minority carrier lifetime in MWIR and long wave infrared (LWIR) HgCdTe, particularly p type, and how it compares to current theories of Auger 7, radiative, and Shockley-Read recombination in this material. The minority carrier lifetime parameter is of particular importance in this regard, and we present some of our recent data for p-type and n-type longwave infrared (LWIR) (x ~ 0.23) and MWIR (x ~ 0.3) HgCdTe and compare them with currently accepted theories of Auger 1, Auger 7, Shockley-Read, and radiative recombination. www.findarticles.com /p/articles/mi_qa3776/is_200506/ai_n14683630   (397 words)

Measurements of Minority-Carrier Lifetimes in n-type Cl-Doped \(\mboxZn_1-x\mboxMn_x\mboxSe\) and ZnSe Epilayers   (Site not responding. Last check: 2007-10-20) We find that the minority carrier lifetime in Cl-doped ZnSe is long and depends upon the majority carrier concentration. However, the addition of small amounts of Mn decreases the minority carrier lifetimes by several orders of magnitude. This appears to suggest that even though the Cl is electrically active with majority carrier concentrations exceeding \(\mbox10^18\) \(\mboxcm^-3\) in these DMS epilayers, the minority-carrier lifetime may be dominated by non-radiative recombination centers. flux.aps.org /meetings/BAPSMAR95/abs/SQ1408.html   (142 words)

Caltech Authors - Correlation between the surface defect distribution and minority carrier transport properties in GaN The surface pits due to threading dislocations were found not to be distributed randomly but on the boundaries of growth columns. The dislocations are thought to be electrically active since the average distance between them (average column size) is comparable to minority carrier diffusion lengths as measured by electron beam induced current experiments on Schottky diodes fabricated with the same material. Diffusion lengths found for holes and electrons are on the order of Lp = 0.28 µm and Le = 0.16 µm which corresponded to the sizes of regions free from surface dislocations in both cases and can be described by a simple model of recombination on grain boundaries. resolver.caltech.edu /CaltechAUTHORS:BRIapl98   (305 words)

ECS EPrints Service - The MOS Inversion Layer as a Minority Carrier Injector EPrints is free software developed by the University of Southampton to facilitate Open Access to research. The MOS Inversion Layer as a Minority Carrier Injector Udrea, F., Amaratunga, G. J., Humphry, J., Clark, J. and Evans, A. The MOS Inversion Layer as a Minority Carrier Injector. eprints.ecs.soton.ac.uk /1165   (112 words)

Minority Charge Carrier Lifetime in Silicon If some of a Si solar cell's generated carriers recombine at defects, impurities, surface damage, etc. before reaching the contacts, the current output is diminished. , because they determine impurity levels and defect structures that give rise to carrier recombination sites. Impurity incorporation, segregation, and evaporation during the crystal-growth process can be altered via ambient choice, growth rate, number of solidification steps, choice of container, heat-source characteristics, selection of source material, and other factors that vary from one process to another. www.siliconsultant.com /SIlifetime.htm   (724 words)

Ideal transistor model This and other similar relations will be used to construct the charge control model of the bipolar junction transistor in section 5.5.2. In steady state and applied to the quasi-neutral region in the base, the continuity equation yields the base recombination current, I The minority carrier lifetime in the base is 10 ns.Calculate the emitter efficiency, the base transport factor, and the current gain of the transistor biased in the forward active mode. ece-www.colorado.edu /~bart/ecen3320/newbook/chapter5/ch5_3.htm   (1582 words)

Demetrius at The Australian National University: Item 1885/43098 Influence of reactive ion etching on the minority carrier lifetime in P-type Si Authors: A defect with energy position at (0.31 ± 0.02) eV was detected by DLTS in RIE p-Si, whereas no defect level was measured in n-type Si. We demonstrate that this energy level could be used to adequately model the injection-dependence of the measured carrier lifetimes using the Shockley-Read-Hall model. hdl.handle.net /1885/43098   (204 words)

Minority Media and Telecommunications Council Minority Ownership (including access to capital and distress sales) The FCC's Consideration of Minority Media Ownership Proposals - November 14, 2006 How the FCC Inhibited Minority Ownership - October 5, 2006 www.mmtconline.org /law   (534 words)

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