Direct growth of orthorhombic Hf 0.5 Zr 0.5 O 2 thin films for hysteresis-free MoS 2 negative capacitance field-effect transistors

Herein, the direct growth of polar orthorhombic phase in Hf 0.5 Zr 0.5 O 2 (HZO) thin films is reported using Pulsed Laser Deposition (PLD). The growth of HZO onto a preheated (700 °C) silicon substrate mimics the rapid thermal annealing, which allows the formation of smaller crystallites (~9.7 nm) with large surface energy leading to the stabilization of metastable orthorhombic phase. Unlike atomic layer deposition (ALD) of HZO, PLD is more advantageous for depositing highly crystalline thin films through optimized parameters, such as laser fluence and background gas pressure. Further, the PLD -HZO is integrated with HfO 2 dielectric and the resulting gate stacks have been used in the bottom gate FET architecture-‘Si// PLD -HZO/HfO 2 /MoS 2 //Ti/Au’. The NCFETs have yielded a sub-thermionic subthreshold swing (SS for = 33.03 ± 8.7 mV/dec. and SS rev = 36.4 ± 7.7 mV/dec.) and a negligible hysteresis (~28 mV), which is capable in realizing low power integrated digital/analog circuits.