IQE III-V, United Kingdom
IQE has expanded the range of compound semiconductor materials being produced at its facilities in the UK and US. It reports increasing demand for wafers used in consumer applications, particularly for optical devices such as lasers and receivers for CD and DVD units. The company has invested over £100 million in the facilities over the last five years and employs around 270 people. IQE uses both Molecular Beam Epitaxy (MBE) and MOCVD (Metal Organic Chemical Vapour Deposition) for producing epitaxial materials.
IQE also manufactures a range of substrates from Gallium Arsenide (3in and 4in substrates, with 6in being added), Indium Phosphide (2in, 3in and 4in) and other specialist III-V materials using both Vertical Gradient Freeze (VGF) and Czochralski (LEC) growth techniques. Substrates are produced for electronic and optoelectronic devices, and high purity bulk polycrystalline feedstock to the rest of the industry.
COMPOUND SEMICONDUCTORS MIX AND MATCH CHARACTERISTICS
Unlike silicon, which is a single element semiconductor and so has a fixed set of electronic characteristics, compound semiconductors are made from a mixture of elements from the group III and V columns of the periodic table. Engineers can therefore make materials with a diverse range of optoelectronic and electronic properties.
In particular, compound semiconductors are extremely efficient at generating light from electricity and converting light back into electricity. They have therefore been key materials for semiconductor lasers, LEDs and detectors. These are at the heart of almost all optoelectronic systems, including fibre-optic communication, optical storage, display technology and satellite power systems.
Electron speed in some III-Vs can be ten times that in silicon, enabling the operation of much higher frequency systems, with lower noise and higher efficiency. They have therefore established themselves in critical circuits of many electronic systems including mobile telephony, satellite communications, cars and trucks, and more.
EPIWAFERS FOR TELECOMS, CD-ROM, DVD AND PRINTERS
Major product lines at IQE include epiwafers for telecommunication lasers, LEDs, and detectors, GaAs/InP HBT and PHEMT epiwafers for electronic materials, and AlGaAs lasers for CD-ROM and high power applications. Visible laser applications include DVD, laser pointers, barcode scanners and laser printers.
Substrates come from IQE's Milton Keynes facility, electronic products from the US fab, and optical materials from Cardiff.
OPTICAL MATERIALS FROM CARDIFF FAB
The Cardiff factory concentrates on generic and custom optical materials, again produced using MBE or MOCVD.
Visible laser diode epiwafers have wavelengths between 635nm and 690nm. Typical uniformities are <5nm and defect densities <50/cm².
VCSELs between 650nm and 980nm have good uniformities and tolerances (<1nm and ±1nm respectively) for MQW PLs.
InGaAs PIN detector materials have excellent thickness (<1%), doping (<6%) and composition (<800ppm) uniformity. Low background doping levels yield low dark currents. Post-growth Zn diffusion is available for planar devices.
IQE's Cardiff fab also supplies Avalanche Photodiodes (APDs), Al-free active laser diodes, 1,310nm and 1,550nm and RCLED epiwafers.
IQE equipment includes VG's V150 multi-wafer MBE production system. This multi-6in MBE system works with GaAs based microwave electronic devices and some high performance phosphide-based optoelectronic devices.
AlInGaP, GaAs or InP based materials, as well as GaInN and SiC, can be processed using Aixtron's MOVPE (Metal Organic Vapor Phase Epitaxy) reactors. IQE also uses Riber MOVPE reactors. The technique is popular throughout the industry for nitride based wide bandgap heterostructures for electronics and optoelectronics.
1,287nm VCSELs ON STANDARD MOCVD
IQE is heavily involved with fundamental research into compound semiconductors, and has co-operated with a large number of research institutes and organisations. One collaborative project studied Vertical Cavity Surface Emitting Lasers (VCSELs). These devices, which are produced at the Cardiff fab, work at infrared and visible wavelengths and go into short-haul fibre links, CD-ROM and other key applications.
VCSELs operating at shorter wavelengths have been in production for some time, and are used in commercial applications and short-distance multimode fibre links for data communications. IQE, for example, already supplies 650nm, 780nm, 850nm and 980nm substrates.
The company, along with three other research partners, has also produced early versions of 1,287nm GaInNAs VCSELs using standard MOCVD. These long wavelength devices are needed for long-range optical communications as previous devices needed a sophisticated design and complex fabrication. The partners also produced 1,268nm and 1,303nm versions. They are now studying long-term stability, and are optimising the MOCVD growth process.
IQE SUPPLIES WAFERS FOR SILICON AND COMPOUND MARKETS
IQE plc was formed in May 1999 by the merger of two leading compound semiconductor wafer foundries, each of which supplied high quality electronic and optoelectronic materials produced using MBE and MOCVD. IQE now produces compound semiconductor epiwafers at production sites in both the UK and USA.
IQE's compound semiconductor epiwafer technology has been extended to the supply of substrates through its Wafer Technology division. IQE Silicon Compounds provides epitaxial services to the silicon semiconductor market, and is a wholly owned subsidiary of IQE plc.