The automation of electrochemical atomic layer epitaxy (EC-ALE) for the production of thin film semiconductors
Flowers, Billy Hugh
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Presented here are the details of the automation of a novel yet attractive methodology of producing thin film semiconducting structures. This method, electrochemical atomic layer epitaxy, or EC-ALE, offers many advantages over conventional methods. Most important of these are the benefits to be gained in the ability to fabricate semiconducting thin films at room temperatures and pressures. Also of note is the EC-ALE process’ ability to minimize waste production, both in volume and toxicity. EC-ALE is the electrochemical analog of atomic layer epitaxy (ALE). EC-ALE employs under potential deposition (UPD) to deposit atomic monolayers of a compound semiconductor’s constituents in repetitive cycles. Automation of these cycles allows for their faithful repetition, up to 1500 times or more. The number of cycles deposited in an experiment determines the thickness of the EC-ALE electrodeposit. |The evolution and development of the automation hardware is discussed in depth. The efficacy of the hardware has been evaluated by forming EC-ALE deposits of both CdTe and CdSe semiconductors. These deposits were analyzed by electron microprobe spectroscopy (EPMA), grazing angle X-ray diffraction (XRD), scanning infrared absorption, and optical microscopy as feedback, both to improve upon the implementation of EC-ALE and as a barometer of various hardware configurations.