Glossary

ALD

Atomic Layer Deposition. A method for producing ultra thin films for semiconductor devices and new, emerging non-semiconductor applications. ALD is a technology that is capable of meeting scaling production requirements of next-generation geometries (45 nm and below). The ALD process is used to pulse and purge two reactants to deposit films. The purge process is done using carrier gases like Argon or nitrogen.

AlGaAs

Aluminium Gallium Arsenide; compound semiconductor material

AlGaN

Aluminium Gallium Nitride; compound semiconductor material

Annealing

Heat treatment that alters the physical and sometimes chemical properties of a material to increase its ductility and reduce its hardness, making it more workable. It involves heating a material above its recrystallization temperature, maintaining a suitable temperature for an appropriate amount of time, and then cooling.

Carrier

Is a particle or quasiparticle that is free to move, carrying an electric charge, especially the particles that carry electric charges in electrical conductors. Examples are electrons, ions and holes.

Carrier lifetime

The time that takes carriers i.e. electrons(-) and holes(+) to recombine inside of a semiconductor device.

Chip

The finished device structure which constitutes a very small element of the semiconductor wafer.

Cleanroom

The place in a semiconductor fab where all wafer processing is done. Dust and particles which might fall on the wafers during processing and result in the circuits not functioning correctly are kept out of the cleanroom by filtering the air and managing the airflow.

CMOS

Complementary Metal Oxide Semiconductor is a major class of integrated circuits. CMOS technology is used in chips such as microprocessors, microcontrollers, static RAM, and other digital logic circuits. CMOS technology is also used for a wide variety of analog circuits such as image sensors, data converters, and highly integrated transceivers for many types of communication devices.

COD

Catastrophic optical damage. Catastrophic optical damage (COD), or catastrophic optical mirror damage (COMD), is a failure mode of high-power semiconductor lasers. It occurs when the semiconductor junction is overloaded by exceeding its power density and absorbs too much of the produced light energy, leading to melting and recrystallization of the semiconductor material at the facets of the laser. 

Compound

semiconductors

These multi-element semiconductors are complex crystal growth structures containing a variety of material elements. They are defined by the periodic table groups they come from. For example: IV/IV (germanium/silicon), III/V (gallium/nitrogen), II/VI (magnesium/oxygen). Compound semiconductors have several advantages compared to single element semiconductors. Many have properties that allow them to emit or absorb light very efficiently (for illumination or production of electrical energy). Many can be processed into devices that have better power capabilities, operation frequency, or efficiency than similar devices made from silicon only.

Conductor

A material that allows energy flow to pass through it easily. In our case, this refers usually to an electrical conductor, which allows electricity flow. It may sometimes refer also to heat conductor. In thermal conduction, the heat is transferred by the oscillation of atoms inside the material. In electrical conduction, the electrons themselves move in order to create the current.

CPV

Concentrated photovoltaics - A photovoltaic technology that generates electricity from sunlight. Unlike conventional photovoltaic systems (rooftop solar cells), CPVs use lenses or curved mirrors to focus sunlight onto small, highly efficient, multi-junction (MJ) solar cells. They possess the highest efficiency of all existing PV technologies, but they are still expensive to manufacture. Hence, they are applied mostly in high-end applications like in military/space technology.

Crystalline Oxide

A very thin layer of material formed by the material surface atoms and oxygen atoms. The layer is formed on top of a clean III-V material surface if a very controlled environment is arranged (ultra-high vacuum with certain oxygen pressure, temperature, time). Its thickness ranges from few atomic layers to few nanometres. In a crystalline oxide, atoms obey certain arrangement/period /symmetry. This symmetry depends on the material itself and the environment in which the crystalline oxide was formed.

CVD

Chemical Vapor Deposition is the deposition of thin films (usually dielectrics/insulators) on silicon wafers placed in a reactor chamber or furnace. The target deposition material is delivered to the surface of the wafer in the form of a mixture of gases which then react at the surface of the wafers. CVD can be done at medium to high temperature in a furnace, or in a CVD reactor in which the wafers are heated but the walls of the reactor are not. Plasma enhanced CVD avoids the need for high temperature by exciting the reactant gases into a plasma.

Deposition

A process in which material-carrying gases are introduced into the reactor chamber where the required crystal growth or deposition process occurs on the wafers. Depending on the kind of coating process, different electronic and optoelectronic devices can be manufactured, e.g. LEDs, lasers, solar cells or transistors.

Detector

/photodetector

A compound semiconductor that is able to convert incoming light of any wavelength into electrical energy. Detectors are required for optical communication systems.

Die

An individual chip

Dielectric

Insulator

Diode

An electronic device which permits significant current flow in only one direction. Diodes typically function as a rectifier, i.e., converting alternating current into direct current.

Display

An electronic device for displaying images and text. Displays can be found in many industrial and consumer electronic products, e.g. in digital cameras, cell phones or navigational equipment, as well as in flat screen televisions.

Epitaxy

The deposition of thin single crystalline layers on a suited substrate in the form of crystal growth.

Epiwafer

A wafer made from semiconductor material by epitaxial growth for use in photonics, microelectronics, spintronics, or photovoltaics.

EQE

External quantum efficiency. A ratio of extracted photons over injected charges.

Etching

Etching is used in microfabrication to chemically remove layers from the surface of a wafer during manufacturing. It is a critically important process module, and every wafer undergoes multiple etching steps before it is complete.

Facet

One side of a geometric shape. The organization of naturally occurring facets was key to early developments in crystallography, since they reflect the underlying symmetry of the crystal structure.

GaAs

Gallium Arsenide

GaN

Gallium Nitride

Gate

An element of a transistor to which voltage may be applied in order to turn a circuit on or off. A gate structure requires the use of insulating materials to allow the buildup of an electrical field.

HEMT

High Electron Mobility Transistor. It is a field effect transistor incorporating a junction between two materials with different band gaps. A commonly used material combination is GaAs with AlGaAs. HEMTs have attracted attention due to their high-power performance capabilities, especially for high frequency applications.

InGaAlP

Indium Gallium Aluminum Phosphide

InP

Indium Phosphide. Important compound semiconductor used in i.e. communication lasers.

Insulator

A material which does not allow electric current to flow through it. In semiconductor chips, commonly used insulators are silicon dioxide (glass) and silicon nitride (silicon + nitrogen). Also commonly referred to as a dielectric in the semiconductor industry.

IQE

Internal quantum efficiency. Internal quantum efficiency refers to the efficiency with which photons that are not reflected or transmitted out of the chip can generate collectable carriers.

Laser

A laser diode, (LD), injection laser diode (ILD), or diode laser is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with electrical current creates lasing conditions at the diode's junction. Laser diodes can directly convert electrical energy into light. 

Laser facet

The flat surfaces of side edge emitting lasers from where the laser beam emerges. 

LCD

Liquid crystal display.

LED

Light-emitting diode. An electronic semiconductor device that can emit very bright light and is highly energy-efficient. Most commonly used LEDs  have an area of 0.1 mm2 (ca. 20 mA) whereas the most powerful LEDs can have an area of 1 mm2 (ca. 350 mA) or more. This places LEDs among the world's smallest light sources and their low power consumption and heat emission qualities make LEDs far more economical than traditional lighting.

Light emitter

Light emitters, for example a laser or LED, convert electrical energy into light. The opposite of a light emitter is a detector.

MBE

Molecular Beam Epitaxy. A method in which raw materials sit in vessels inside the equipment or reactor and evaporate under extremely low pressure - around one millionth of normal atmospheric pressure. The advantage of this method is that the low pressure allows for greater semiconductor purity. The disadvantage is that the creation of a vacuum makes the process the most expensive and production is limited to small volumes. Also, not all materials can be produced with the MBE method.

microLED

An LED less than 50 microns in size.

Micron

One thousand microns make one millimeter. A human hair is about 100 microns thick.

microLED

An LED sized between 150 and 50 microns.

MOCVD

Metal-Organic Chemical Vapor Deposition. With this compound semiconductor production method, the raw material "metal-organic compounds" are transformed into gases and then, bound to a carrier gas and subsequently fed into the reactor. This transformation also occurs under reduced pressure, down to approx. one-tenth of normal atmospheric pressure. The advantage is that the gases introduced are of high purity and can be finely dosed. MOCVD equipment allows the processing of quite large surface areas and is therefore first choice for the production of compound semiconductors. 

MOSFET

The metal–oxide–semiconductor field-effect transistor. Type of insulated-gate field-effect transistor that is fabricated by the controlled oxidation of a semiconductor, typically silicon

Multijunction cell

Solar cell which constitutes multiple PN-junctions that are designed and fabricated to absorb certain wavelength range of light.

Nanometer

One thousand-millionth of a meter. 70,000 times thinner than a human hair.

Nanotechnology

The term refers to the research conducted in cluster physics and surface physics, surface chemistry, semiconductor physics, specific areas of chemistry and, to a more limited extent, in areas of mechanical engineering and food technology ("nano food"). The collective term is derived from the magnitude common to all of the research areas, namely, structures with sizes ranging from a single atom to 100 nanometers (nm). 

Native oxide

Oxides that appear naturally on the materials after being exposed to oxygen. These oxides are amorphous structures (atoms have random orientation) with high levels of surface states defects. 

OLED

Organic Light Emitting Diode. An OLED is a solid-state device that typically consists of a series of organic thin films sandwiched between two thin film conductive electrodes. The choice of organic materials and the layer structure determine the device's performance features: emitted color, operating lifetime and power efficiency.

Passivation

In physical chemistry and engineering the term refers to a material becoming "passive," that is, less affected or corroded by the environment. Passivation involves creation of an outer layer of shield material that is applied as a micro coating, created by chemical reaction with the base material, or allowed to build from spontaneous oxidation in the air.

PL

Photoluminescence. Characterization technique to measure the photoluminescence emissions of compound semiconductor materials

Plasma

One of the four fundamental states of matter,  plasma consists of a gas of ions – atoms which have some of their orbital electrons removed – and free electrons. Plasma can be artificially generated by heating a neutral gas or subjecting it to a strong electromagnetic field to the point where an ionized gaseous substance becomes increasingly electrically conductive.

Power electronics

The application field of solid-state electronics to the control and conversion of electric power.  The conversion is performed with semiconductor switching devices such as diodes, thyristors, and power transistors such as the power MOSFET and IGBT.

SEM

Scanning electron microscope. A type of electron microscope that produces images with even 1-10 nm resolution by scanning the sample surface with a focused beam of electrons (electron gun). The electrons interact with atoms in the sample, producing various signals that contain information about the surface topography and composition of the sample.

Semiconductor

A material with conductivity is between that of a conductor and an insulator. Its conductivity can be modulated by adding impurities (such as boron or phosphorus in silicon).

UHV

Ultra-high vacuum is the vacuum regime characterized by pressures lower than about 100 Nano pascal. UHV conditions are created by pumping the gas out of a UHV chamber. At these low pressures the mean free path of a gas molecule is greater than approximately 40 km, so the gas is in free molecular flow, and gas molecules will collide with the chamber walls many times before colliding with each other  

Wafer

The technical term for the substrate material, typically a thin disc of semiconductor material, on which the layers are deposited in the reactor. Wafers are typically 2 inch, 100, 150, 200 or 300 mm in diameter.