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 oxideoxide 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.