Nov 10 2006
The new ECellAs valved Arsenic effusion source or ‘cracker cell’ for molecular beam epitaxy (MBE) from Oxford Instruments is designed for high performance MBE growth of Arsenic-containing III-V materials. Large crucible capacity, fast and precise flux control, and easy, modular handling for maintenance and crucible refill make the ECellAs equally ideal for production and high-throughput development MBE systems in addition to research reactors.
Molecular beam epitaxy enables the growth of semiconductor materials such as Gallium Arsenide (GaAs) for chips in applications such as mobile phones and other communications devices, Indium Arsenide (InAs) for infrared detectors and optoelectronics, and a wide range of other and more complex compound materials which enable modern electronic devices.
The ECellAs has been designed for high-reliability and ease of maintenance: a frequent problem of valved cracker cells, that of valve clogging, is prevented by a unique patented independent heater design. For easy on-site maintenance and service, the unique ECellAs construction allows the reservoir to be individually demounted from the cracker unit, minimising system down-time and removing the need to replace the complete cell or return it for factory service. A heated secondary filling port allows As recharge without needing to empty the crucible first.
“The development of the ECellAs is part of our ongoing commitment to our MBE business within Oxford Instruments since we acquired VG Semicon two years ago,” comments Tony Cornish, Business Manager for MBE and Ion Beam products. “With its high level of reliability and ease of use, the ECellAs offers very significant benefits in terms of cost of ownership and reduced downtime to users of our MBE systems and those of other vendors. Excellent control over MBE growth processes has been demonstrated, with rapid, linear valve response, highly controllable As4 to As2 transition and fast, repeatable As flux modulation.”
With 1 l, 3 l and 8.5 l versions to enable the customer’s desired throughput and campaign length, the ECellAs may be fitted to both Oxford Instruments’ own range of V80H, V90 and V100 MBE reactors and to any other vendors’ MBE systems. The ECellAs reservoir heater design gives complete flexibility to mount the cell in any orientation, and complete automated control if offered via a motorised valve and growth software interface. Further details of the product may be found at www.oxford-instruments.com/ECell.
Valved effusion sources or cracker cells offer significant benefits over the thermal control of conventional open sources for molecular beam epitaxy: a needle valve provides optimised control over the growth process with precise, fast flux modulations and complete flux shut-off which allows the As source to be left continuously at operating temperature without depleting charge material. The As charge capacity may be indiscriminately large without limiting the responsiveness of the source; whether using the 1 l version or the 8.5 l version of the ECellAs, As flux responsiveness remains constant.