9 October 2012

IQE’s III-V-on-Si laser materials enable next-gen hard disk drive technology

Epiwafer foundry and substrate maker IQE plc of Cardiff, Wales, UK says that it has produced epitaxial wafers combining the optical properties of compound semiconductors with the electronic properties of silicon to produce high-power lasers that enable increased storage density for next-generation hard disk drives.

In the last 20 years, through research and technological innovation, typical storage capacities for consumer disk drives have increased by 100,000 times from around 20MB to 2TB, notes IQE. In order to maintain such increases in capacity while maintaining the same footprint, the next generation of disk drives need to be capable of storing more than 1Tb of data per square inch.

Such high-density storage is made possible through heat-assisted magnetic recording (HAMR), where the heat source is a semiconductor laser device emitting 10mW or more of optical power.

Work published in the September edition of Nature Photonics volume 6 (2012) p612 (doi:10.1038/nphoton.2012.204) describes the achievement by Tyndall National Institute (University College Cork), Semprius Inc and Seagate Technology in combining a high-power gallium arsenide (GaAs) laser structure with a silicon substrate using Semprius’ proprietary micro-transfer print technology to print epitaxial layers produced by IQE using metal-organic chemical vapour deposition (MOCVD) at its Cardiff manufacturing facility (‘Wafer-scale integration of group III–V lasers on silicon using transfer printing of epitaxial layers’, Justice et al).

Specifically, the researchers used an elastomeric stamp to selectively release and transfer epitaxial coupons of GaAs to realize III–V lasers on a silicon substrate. Low-threshold continuous-wave (cw) lasing at a wavelength of 824nm has been achieved from Fabry–Pérot ridge waveguide lasers operating at temperatures up to 100°C. Single- and multi-transverse mode devices emit total optical powers of >60mW and support modulation bandwidths of >3GHz.

The fabrication strategy opens up a route to the low-cost integration of III–V photonic devices and circuits on silicon and other substrates. In particular, says IQE, the demonstrated level of optoelectonic integration should allow HAMR to meet growing demand in the high-performance, high-capacity and low-cost storage markets.

“Programs such as this demonstrate how we successfully combine our high-volume manufacturing capabilities with leading-edge research to support our partners through all stages from development through to production,” says Andrew Joel, commercial director for IQE’s optoelectronics division.

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