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3D Transistor

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Tetris

Sun Aug 21 2011, 07:31PM

Registered Member #4016 Joined: Thu Jul 21 2011, 01:52AM
Location: Gainesville, FL
Posts: 660

I read in The Economist that they are making some sort of new transistor, and it involves making it sort of '3d' to lessen the leakage. I also read in the article they are making junctionless transistors. If transistors weren't confusing enough, they made more types of them. Can someone please explain to me transistors and what this new type of transistor is?

Ash Small

Sun Aug 21 2011, 08:23PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

From Wikipedia:

"Point-contact transistor, first kind of transistor ever constructed
Bipolar junction transistor (BJT) Heterojunction bipolar transistor, up to several hundred GHz, common in modern ultrafast and RF circuits
Grown-junction transistor, first kind of BJT
Alloy-junction transistor, improvement of grown-junction transistor Micro-alloy transistor (MAT), speedier than alloy-junction transistor
Micro-alloy diffused transistor (MADT), speedier than MAT, a diffused-base transistor
Post-alloy diffused transistor (PADT), speedier than MAT, a diffused-base transistor
Schottky transistor
Surface barrier transistor

Drift-field transistor
Avalanche transistor
Darlington transistors are two BJTs connected together to provide a high current gain equal to the product of the current gains of the two transistors.
Insulated gate bipolar transistors (IGBTs) use a medium power IGFET, similarly connected to a power BJT, to give a high input impedance. Power diodes are often connected between certain terminals depending on specific use. IGBTs are particularly suitable for heavy-duty industrial applications. The Asea Brown Boveri (ABB) 5SNA2400E170100 illustrates just how far power semiconductor technology has advanced.[19] Intended for three-phase power supplies, this device houses three NPN IGBTs in a case measuring 38 by 140 by 190 mm and weighing 1.5 kg. Each IGBT is rated at 1,700 volts and can handle 2,400 amperes.
Photo transistor

Field-effect transistor Carbon nanotube field-effect transistor (CNFET)
JFET, where the gate is insulated by a reverse-biased PN junction
MESFET, similar to JFET with a Schottky junction instead of PN one High Electron Mobility Transistor (HEMT, HFET, MODFET)

MOSFET, where the gate is insulated by a shallow layer of insulator
Inverted-T field effect transistor (ITFET)
FinFET, source/drain region shapes fins on the silicon surface.
FREDFET, fast-reverse epitaxial diode field-effect transistor
Thin film transistor, in LCDs.
OFET Organic Field-Effect Transistor, in which the semiconductor is an organic compound
Ballistic transistor
Floating-gate transistor, for non-volatile storage.
FETs used to sense environment Ion-sensitive field effect transistor, to measure ion concentrations in solution.
EOSFET, electrolyte-oxide-semiconductor field effect transistor (Neurochip)
DNAFET, deoxyribonucleic acid field-effect transistor

Spacistor
Diffusion transistor, formed by diffusing dopants into semiconductor substrate; can be both BJT and FET
Unijunction transistors can be used as simple pulse generators. They comprise a main body of either P-type or N-type semiconductor with ohmic contacts at each end (terminals Base1 and Base2). A junction with the opposite semiconductor type is formed at a point along the length of the body for the third terminal (Emitter).
Single-electron transistors (SET) consist of a gate island between two tunnelling junctions. The tunnelling current is controlled by a voltage applied to the gate through a capacitor.[20]
Nanofluidic transistor, controls the movement of ions through sub-microscopic, water-filled channels. Nanofluidic transistor, the basis of future chemical processors
Multigate devices Tetrode transistor
Pentode transistor
Multigate device
Trigate transistors (Prototype by Intel)
Dual gate FETs have a single channel with two gates in cascode; a configuration optimized for high frequency amplifiers, mixers, and oscillators.

Junctionless Nanowire Transistor (JNT), developed at Tyndall National Institute in Ireland, was the first transistor successfully fabricated without junctions. (Even MOSFETs have junctions, although its gate is electrically insulated from the region the gate controls.) Junctions are difficult and expensive to fabricate, and, because they are a significant source of current leakage, they waste significant power and generate significant waste heat. Eliminating them held the promise of cheaper and denser microchips. The JNT uses a simple nanowire of silicon surrounded by an electrically isolated "wedding ring" that acts to gate the flow of electrons through the wire. This method has been described as akin to squeezing a garden hose to gate the flow of water through the hose. The nanowire is heavily n-doped, making it an excellent conductor. Crucially the gate, comprising silicon, is heavily p-doped; and its presence depletes the underlying silicon nanowire thereby preventing carrier flow past the gate."

Thomas W

Sun Aug 21 2011, 08:41PM

Registered Member #3324 Joined: Sun Oct 17 2010, 06:57PM
Location:
Posts: 1276

wow thats alot of transistors :O
has anyone ever seen or used all of them XD

Mattski

Sun Aug 21 2011, 10:49PM

Registered Member #1792 Joined: Fri Oct 31 2008, 08:12PM
Location: University of California
Posts: 527

I believe 3D transistors in the media are typically referring to "Fin-FETs" or "Tri-gate FETs" which are built by Intel and others

They are normal MOSFETs but instead of the gate just being on top of the channel, the surface has been etched so that the gate can surround the channel on three sides. The benefit of this I believe is that with the very short gate-length devices used for ultra high speed circuits is that there tends to be a lot of current leaking through even when the device is supposed to be off because the channel is so short. With a longer channel it is harder for electrons to leak all the way across. This is a problem because it means the chip draws extra power and heats up more. Surrounding the channel on three sides instead of just one side with a gate allows the channel to be more completely turned off when it's supposed to be, reducing off-state leakage.

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