Platform work package 1: Materials Growth (Epitaxy)

This work package is addressing the key challenge of growing high quality compound semiconductor layers In many cases this involves growth on to substrates with large lattice mismatches A particular focus is the growth on to Si substrates to allow, low cost, large volume manufacturing of the devices being developed with in the Manufacturing Hub


Prof David Wallis (


WP 1 encompasses all the epitaxy activities that are relevant to the CS Hub These include non and semi polar GaN growth for optoelectronics, III As for photonic integration, metamorphic structures on GaAs for magnetic sensors and arsenides and phosphides for optical devices.

Progress and Challenges

In the last year some significant improvements have been made to the capabilities of the hub partners.

  • In Cardiff, a new MOCVD system for growth of Arsenides Phosphides and Antimonides has come on line and has demonstrated growth of all 3 of these materials systems. Basic device structures have been developed and now work is focussed on transferring these on to Si substrates.
  • At UCL funding has been won to install a new MBE tool that will be dedicated to the growth of only Arsenide structures. This will enable layers with much lower background impurities to be achieved.
  • The new system has been installed in the UCL MBE lab and is currently being commissioned.

In terms of project deliverables, many of those defined at the start of the Hub have now been successfully completed. These include, growth of non polar GaN layers on Si with record XRD FWHM values, growth of metamorphic Phosphide based HEMT structures with world leading carrier concentration and mobility and Quantum dot laser structures with record high temperature operation.

Moving forward we have defined a new set of deliverables which focus on some of the manufacturability issues associated with the technologies being developed. These will address issues such as the control of interface strain in GaAs on Si structures, development of patterned structures to control strain and wafer bow in non and semi polar GaN on Si layers and studies of the impact of strain on the processability and yield in metamorphic HEMT structures.

TEM image of an InAs /GaAs Q dot laser structure with a maximum operating temperature of 126oC grown on a Si substrate
Xray FWHM data for non polar GaN grown on Si (left) and sapphire (right) substrates. The FWHM values for these layers are amongst the best reported internationally.

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