Tin Oxide Field-Effect Transistors Deposited by Thermal Atomic Layer Deposition with H2O Reactant

In this work, SnO 2 -based field-effect transistors were fabricated and characterized.SnO 2 channel (Thickness = 6.5 or 9.0 nm) was deposited by thermal atomic layer deposition (T-ALD) with H 2 O as reactant.The conductivity of the channel layer was tuned by a post-annealing process, with annealing temperature limited to 400 ∘ C. When the channel thickness was 9 nm, the channel could not be properly modulated due to high intrinsic carrier concentration.On the other hand, a 6.5-nm thick SnO 2 channel exhibited excellent device characteristics in general, including clear channel pinch-off and current on/off ratio higher than 10 4 .Increasing the annealing duration from 1 to 2 hours led to higher channel conductivity and transconductance, such that the drain current increased by a factor of 2.5 at the given gate and drain biases.On average, the field-effect mobility increased from 110 to 125 cm 2 /Vs, and the subthreshold swing decreased from 4 to 2 V/dec.This work demonstrates that SnO 2 deposited by T-ALD can be an attractive channel material for back-end-of-line compatible transistors, which are crucial for hyper-scaling of current Si technology.