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Topic: Heterojunction

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	Heterojunction Band Alignment
		The central feature of a heterojunction is that the bandgaps of the participating semiconductors are usually different.
		As with all semiconductor devices, the key to understanding the behavior of heterojunctions is the energy-band profile which graphs the energy of the conduction and valence band edges versus position.
		In the earlier literature on heterojunctions, this latter effect is usually described in terms of the electron affinity
	www.utdallas.edu /dept/ee/frensley/technical/hetphys/node7.html (677 words)

	United States Patent Application: 0020071970
		A heterojunction material, comprising: a nanocrystalline titanium dioxide phase; and a second metal oxide phase, wherein the nanocrystalline titanium dioxide phase is chemically bonded to the second metal oxide phase through a heterojunction formed at an interface between the nanocrystalline titanium dioxide phase and the second metal oxide phase.
		The heterojunction material of claim 1, wherein the second metal oxide phase forms a shell around a core comprising the nanocrystalline titanium dioxide phase, the heterojunction formed at the interface between the shell and the core.
		For example, the disclosed nanocrystalline titanium dioxide heterojunction materials are characterized by a red-shift in PE that correlates with the extent of chemical interaction between the nanocrystalline titanium dioxide phase and the second metal oxide phase at their interface.
	appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=/netahtml/PTO/srchnum.html&r=1&f=G&l=50&s1="20020071970".PGNR.&OS=DN/20020071970&RS=DN/20020071970 (6636 words)

	U.S. Patent: 5530272 - High electron mobility transistor including periodic heterojunction interface - June 25, 1996
		The heterojunction interface formed by the carrier channel layer and the carrier supply layer has a periodic undulating shape with convex portions and valley portions in stripe shapes extending parallel to the main current flow direction.
		In addition, it is possible to increase the heterojunction area in the vicinity of the electron supply layer by providing the electron supply layer 16a at the valley portions, whereby the quantity of electrons that is supplied to the heterojunction part per unit chip area can be increased.
		According to this fourth embodiment, since the heterojunction has an undulating shape and the electron supply layer 17 on the valley parts of this undulating shape at a predetermined interval is inactivated, a pseudo one dimensional electron channel can be formed at the stripe shaped convex part.
	www.everypatent.com /comp/pat5530272.html (3440 words)

	Heterojunction thyristor-based amplifier
		Similar to the heterojunction thyristor device, an optical path is provided through the device either vertically or in the waveguide mode, and an input signal is applied to the anode terminal 36 with respect to the injector terminal(s) 38 such that the anode terminal 36 is biased positively with respect to the injector terminal(s) 38.
		The resistors R1 and R2 are used to configure the heterojunction thyristor-based operational amplifier circuit as a inverting amplifier stage whereby the output signal produced at the output node V.sub.o is proportional to the signal supplied from the source V.sub.s by a gain factor (-R2/R1).
		The resistor R and capacitor C are used to configure the heterojunction thyristor-based operational, amplifier circuit as an integration stage whereby the output signal produced at the output node V.sub.o is proportional to the integral of the signal supplied from the source V.sub.s.
	www.devileye.net /catalog/bed_enclosure_baby/heterojunction_thyristor-based_amplifier.html (9350 words)

	Method for forming indium oxide/n-silicon heterojunction solar cells - Patent 4436765
		The prior art has taught a construction of indium oxide heterojunction with p-type silicon whereas the present invention is directed to the formation of a heterojunction between indium oxide and n-type silicon having a thin surface layer of silicon oxide.
		In addition, layer 14 is characterized as being of a specific thickness and having an index of refraction to act as an anti-reflection coating thus suppressing the reflectivity of the silicon surface.
		As presently understood, in the formation of the heterojunction between the indium oxide and the oxidized silicon substrate the depletion region or barrier region is contained within the silicon substrate 10.
	www.freepatentsonline.com /4436765.html (3435 words)

	United States Patent Application: 0020053679
		The III-V p-n heterojunction device of claim 12, wherein a concentration of said at least one acceptor impurity metal within said p-type III-V compound layer is in the range of 10.sup.18 to 10.sup.21 atoms cm.sup.-3.
		The III-V p-n heterojunction device of claim 16, wherein a concentration of said at least one acceptor impurity metal within said second p-type III-V compound layer is in the range of 10.sup.18 to 10.sup.21 atoms cm.sup.-3.
		The III-V p-n heterojunction device of claim 16, wherein a concentration of said at least one acceptor impurity metal within said second p-type III-V compound layer is in the range of 10.sup.19 to 10.sup.20 atoms cm.sup.-3.
	appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/PTO/search-bool.html&r=2&f=G&l=50&co1=AND&d=PG01&s1=vassilevski.IN.&OS=IN/vassilevski&RS=IN/vassilevski (8084 words)

	Bipolar Junction Transistors
		Heterojunction bipolar transistors are bipolar junction transistors, which are composed of at least two different semiconductors.
		Since a heterojunction transistor can have large current gain, even if the base doping density is higher than the emitter doping density, the base can be much thinner even for the same punchthrough voltage.
		The fundamental restriction of heterojunction structures still applies, namely that the materials must have a similar lattice constant so that they can be grown without reducing the quality of the material.
	ece-www.colorado.edu /~bart/book/book/chapter5/ch5_7.htm (653 words)

	Journal of Electronic Materials: Planar p-on-n HgCdTe heterojunction mid-wavelength infrared photodiodes formed using ... (Site not responding. Last check: 2007-11-04)
		An advantage of planar heterojunction photodiodes over homojunction photodiodes is a consequence of the reduced influence of recombination at the semiconductor surface due to the wider bandgap-capping layer, thus resulting in reduced surface dark current leakage.
		Most commercial P-on-n heterojunction photodiodes are based on the mesa isolation technique, where etching of surrounding p-type material is used to delineate and isolate the detectors.
		During the etching process, the junction that terminates at the etched surface is exposed to potential contamination from the ambient, leading to a possible increase in surface currents at the junction perimeter, with the amount of leakage strongly dependent on the subsequently formed passivation layer.
	www.findarticles.com /p/articles/mi_qa3776/is_200307/ai_n9261019 (1211 words)

	Heterojunction Device - Field Effect Transistor patents
		In a semiconductor film having a heterojunction structure, for example a semiconductor film (11) including a SiGe layer (2) and a Si layer (3) formed on the SiGe layer (2), impurity concentration is controlled in such a manner that the concentration of impurity in the lower, SiGe layer (2) becomes...
		A heterojunction transistor may include a channel layer comprising a Group III nitride, a barrier layer comprising a Group III nitride on the channel layer, and an energy barrier comprising a layer of a Group III nitride including indium on the channel layer such that the channel layer is between...
		The semiconductor device in which a field effect transistor utilizing a heterojunction is formed in a device formation region sectioned by a device separation region of a substrate comprising a semiconductor layer laminated while including a semiconductor layer having a heterojunction on a semiconductor substrate.
	www.freshpatents.com /x1257192000psbc.php (6241 words)

	Normal Template for MS Office 97 (Site not responding. Last check: 2007-11-04)
		Since in an efficient heterojunction (either wide-gap emitter or narrow-gap base), hole injector into the emitter is suppressed, the emitter delay caused by carrier storage in the emitter becomes negligible.
		Moreover, Si/SiGe heterojunction bipolar transistor is an attractive candidate that is in compatibility of the material and of the process with state to the art silicon technology at minimum extra cost.
		In addition to the increase of current gain, the heterojunction structure reduces the base resistance owing to the possibility of increasing the base doping further.
	www.glue.umd.edu /~hxwu/chapter22.html (666 words)

	Heterojunction - ArticleWorld (Site not responding. Last check: 2007-11-04)
		Each material involved in a heterojunction has a different energy band gap, thereby giving a certain desired behaviour to the heterojunction.
		Several of a diode model’s specifications that decide that voltage response for a certain diode current value can be tuned according to requirements by adjusting the thickness of semiconductor layers and taking into consideration their band gaps.
		When alternating layers of heterojunctions are used as base-emitter junctions of bipolar junction transistors (BJT), high forward gain and low reverse gain values are observed.
	www.articleworld.org /index.php?title=Heterojunction&printable=yes (497 words)

	Saturday morning, 13 April 1996 (Site not responding. Last check: 2007-11-04)
		The development of a clear understanding of these degradation phenomena, their relation to the semiconductor materials and device structure, and their dependence on the electrical and thermal stress conditions is needed for device development for commercial applications.
		For the emitter-base heterojunction, out-diffusion of the base dopant into the emitter causes a shift of the p-n junction into the emitter and degradation in the current gain.
		In addition, a thin AlGaAs layer was left when the emitter mesa was etched to form a depleted heterojunction covering the base surface between the emitter mesa and base contact to reduce the surface recombination current which typically dominates the base current.
	www.physics.ohio-state.edu /~wilkins/osaps/program/G.html (1378 words)

	Heterojunction solar cell - Patent 5342453
		A high-efficiency single heterojunction solar cell wherein a thin emitter layer (preferably Ga.sub.0.52 In.sub.0.48 P) forms a heterojunction with a GaAs absorber layer.
		A further object of the invention is to use a thin emitter layer of defined composition over a GaAs absorber layer in a heterojunction solar cell having a 1-sun energy conversion efficiency of greater than 25%.
		A schematic of a single heterojunction GaInP/GaAs solar cell having an AR coating is shown in FIG.
	www.freepatentsonline.com /5342453.html (2276 words)

	2
		The energy band diagrams for isotype heterojunctions utilize the same expressions as were derived for the anisotype cases [3].
		However, in these isotype heterojunctions modelling we simply modified the previous derived equations and reconsider the built in voltage for the isotype heterojunctions.
		The expressions for the energy band diagrams are similar to the p-N heterojunction case with Na replaced by N
	ice.prohosting.com /~jwah/nnpp.html (428 words)

	Scanning Probe Characterization of III-V Heterojunction Bipolar Transistor Structures (Site not responding. Last check: 2007-11-04)
		Advanced semiconductor heterostructure devices rely increasingly upon the ability to characterize, and ultimately to control, composition and the associated electronic structure in a device with nanometer-scale spatial resolution.
		Of particular interest in this project is the characterization of electronic structure in III-V semiconductor heterojunction bipolar transistors, which are of outstanding current interest for a wide range of applications in high-speed and high-power electronics.
		Accurate characterization of and control over the vertical compositional and dopant profiles, which directly influence the electrostatic potential distribution within such a device, at or near the manometer scale is essential for analysis and optimization of device performance.
	www.ucop.edu /research/micro/abstracts/98_183.html (166 words)

	Journal of Electronic Materials: MBE-grown HgCdTe multi-layer heterojunction structures for high speed low-noise ... (Site not responding. Last check: 2007-11-04)
		Small values of k, the ratio of electron to hole ionization coefficients, are important to minimize excess noise and maximize gain at high avalanche gain.
		A dark current of 1.3 IA measured at a gain of x 9.8, suggesting that further reduction in defect density in the multi-layer heterojunction structure will be necessary to improve the detector performance for high speed and low noise operation.
		Efforts are underway to reduce the defect density in the multi-layer heterojunction structure using lattice-matched Cdo.^sub 0.98^Zn^sub 0.02^Te substrates in order to reduce dark current.
	www.findarticles.com /p/articles/mi_qa3776/is_199706/ai_n8771083 (1010 words)

	Ordered Bulk Heterojunction Photovoltaic Cells - GCEP
		Careful analysis and optimization of each process that occurs in bulk heterojunction PV cells will be carried out and devices based on ordered interpenetrating networks of organic and inorganic semiconductors will be created.
		In this study, well-ordered interpenetrating networks of organic and inorganic semiconductors will be made to create bulk heterojunction PV devices instead of the disordered blends that have been used in the past.
		The forward transfer from the polymer to the electron accepting material must occur before the electron and hole in the exciton undergo geminate recombination, and back electron transfer from the electron acceptor to the polymer must be inhibited.
	gcep.stanford.edu /research/factsheets/nanostructured_photovoltaic.html (951 words)

	Controlled growth of a molecular bulk heterojunction photovoltaic cell (Site not responding. Last check: 2007-11-04)
		organic photovoltaic cells through the use of the bulk heterojunction (BHJ), where the distance an exciton must diffuse from its generation to its dissociation site is reduced in an interpenetrating network of the donor and acceptor materials.
		However, the random distribution of donor and acceptor materials in such structures can lead to charge trapping at bottlenecks and cul-de-sacs in the conducting pathways to the electrodes.
		This results in a substantial increase in power conversion efficiency compared with the best values obtained by 'random' small-molecular-weight BHJ solar cells formed by high-temperature annealing, or planar double heterojunction photovoltaic cells using the same archetypal materials systems.
	www.nature.com /doifinder/10.1038/nmat1285 (256 words)

	Incoherent Light Emitter Structure - With Heterojunction patents
		With Heterojunction patent applications listed are from June 2005 to current and include Date, Patent Application Number, Patent Title, Patent Abstract summary and are linked to the corresponding patent application page.
		An epitaxial substrate for manufacturing field effect transistor (FET) that has heterojunction structure consisting of at least a channel layer made of gallium nitride or gallium indium nitride and a barrier layer made of aluminum gallium nitride formed successively on the principal plane of the sapphire substrate, wherein the principal...
		In photonic integrated circuits (PICs) having at least one active semiconductor device, such as, a buried heterostructure semiconductor laser, LED, modulator, photodiode, heterojunction bipolar transistor, field effect transistor or other active device, a plurality of semiconductor layers are formed on a substrate with one of the layers being an active...
	www.freshpatents.com /x1257094000psbc.php (6594 words)

	NCSR - Heterojunction Bipolar Transistor
		The HBT is an active bipolar device which incorporates a heterojunction between a wide bandgap semiconductor and narrow bandgap semiconductor, some common materials used are:
		The SHBT has a single heterojunction where the emitter is the wide bandgap material, this allows heavy doping of the base for reduced base resistance while the emitter is more lightly doped reducing the capacitance and improving the high frequency performance.
		The DHBT (Double Heterojunction Bipolar Transistor) has a wide bandgap collector and emitter, allowing the same advantages of the SHBT, with the additional improvement of increased breakdown voltage and decreased minority carrier injection from the base to the collector in saturation mode.
	www.onr.navy.mil /sci_tech/information/312_electronics/ncsr/devices/hbt.asp (350 words)

	Heterojunction Diode Manufactured With SRC Light (Site not responding. Last check: 2007-11-04)
		In a major step forward in the field, Professor Dowben’s research team from the University of Nebraska has shown (see accompanying figure) that a heterojunction can be fabricated by this technique.
		The rectifying behavior of the current versus voltage curves for a diode grown with the use of synchrotron radiation assisted decomposition can be seen identified by the solid line, and the curves for the plasma enhanced CVD grown diodes, the more conventional fabrication technique, are identified by the broken lines.
		For example, recent refinements of the method have shown that transistor fabrication is possible, which is one more step along the quest for direct-write microelectronic components.
	www.src.wisc.edu /about_SRC/news/newsletter/1994/94_12/DOWBEN.HTML (411 words)

	Class Definition for Class 257 - ACTIVE SOLID-STATE DEVICES (E.G.,TRANSISTORS, SOLID-STATE DIODES)
		76, 78, 85, 90, and 94-97, for heterojunction light emitter.
		85, 184-189, for heterojunction in light responsive device.
		for wide band gap emitter heterojunction bipolar transistor.
	www.uspto.gov /go/classification/uspc257/defs257.htm (4228 words)

	ECS EPrints Service - SiGe heterojunction bipolar transistors on insulator
		The three approaches commonly used to produce SiGe HBTs are described and compared, namely the drift SiGe base, the SiGe base with a low doped emitter and the selective SiGe base.
		Methods for suppressing or avoiding transient enhanced boron diffusion are discussed, especially the use of carbon in the SiGe base.
		Finally, work on SiGe heterojunction bipolar transistors on SOI at Southampton University is reviewed.
	eprints.ecs.soton.ac.uk /4722 (201 words)

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