Atomic-layer-deposited LaAlO3/SrTiO3 all oxide field-effect transistors

We have demonstrated well-behaved accumulation-mode all oxide NMOSFETs with amorphous atomic-layer-deposited (ALD) LaAlO₃ gate dielectric stacks on crystalline SrTiO₃ substrates. A maximum drain current exceeding 10 mA/mm has been obtained on a 3.75μm-gate-length device, proving a very conductive channel can be formed at the oxide-oxide interface. Four different gate dielectric stacks, which are Lafirst cycle LaAlO₃, Al-first cycle LaAlO₃, LaAlO₃ with 1.5 nm La₂O₃ interfacial layer, and LaAlO₃ with 1.8 nm Al₂O₃ interfacial layer, have been deposited on SrTiO₃ substrates to systematically study their effects on the conductivity at the different oxide-oxide interfaces. The experimental results show that a La-initiated interfacial layer is preferable to form a more conducting channel at the LaAlO₃/SrTiO₃ interface. Low temperature characteristics have also been utilized to provide an in-depth understanding of the channel formation at the oxide-oxide interface. The availability of the MBE technology to epitaxially grow SrTiO₃ on Si substrate provides the pathway to integrate ALD LaAlO₃/SrTiO₃ devices on Si platform.