Leakage current in single electron device due to implanted gallium dopants by focus ion beam

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Focus ion beam (FIB) technology has been employed to fabricate quantum dot based devices such as the single electron transistor (SET) on a silicon substrate with Cr/Au/Al2O3 film stack. It was discovered that the dwell time of FIB gallium beam on an area impacted the dosage of gallium ions implanted into the insulating substrate, creating a highly doped region which could lead to device leakage current. This work focus on the potential electron transport possible when an over-dosed gallium rich Al2O3 layer will lead to leakage current between otherwise electrically isolated contact pads. Using the Keithley 4200 semiconductor parametric analyzer (SPA) and the energy dispersive X-ray spectrometer (EDS) analysis; we demonstrate the detrimental effect of leakage current in the range of pA, observed between drain/source electrodes due to the high dose of gallium implanted into the insulating Al2O3. The optimized FIB etching parameters to produce a high quality of device functionality with no leakage current is also demonstrated.

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Copyright © 2011 Elsevier B.V. All rights reserved. Publisher's version of record: https://doi.org/10.1016/j.mee.2011.02.114

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Microelectronic Engineering