Abstract
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•Ge gate MOS devices were investigated due to its applicability to sub 16nm node pMOST technology.•GeO2/Al2O3/HfO2 gate stacks were grown by a combined MBE and ALD technique.•Devices were characterised by various physical and electrical methods.•Devices were found to have low EOT and leakage currents and have small hysteresis.
High-κ dielectric gate stacks comprising HfO2 were fabricated on Ge with alumina as the barrier level. This was achieved by thermal annealing in an ultra high vacuum to remove the native oxide followed by deposition of aluminium by molecular beam epitaxy. After in situ oxidation at ambient temperature, HfO2 was deposited by atomic layer deposition. The devices underwent physical and electrical characterisation and show low EOT down to 1.3nm, low leakage current of less than 10−7Acm−2 at ±1V, and CV hysteresis of ∼10mV.