A First-Principles Study on the Stable Phase in Yttrium-Doped HFO₂

Hafnium oxide has been widely used in IC processes, but the explanation of its stable ferroelectricity remains controversial. This article investigated the effects of yttrium doping on the properties of HfO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> through first-principles calculations. The results illustrated that the formation energy of oxygen vacancy is 17.8% lower with yttrium doping. In highly oxygen-deficient YHf <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> o <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</inf> , the cubic phase is stable and the monoclinic-cubic phase transition barrier is reduced by 39%. The doping-defect coupling model is expected to explain the ferroelectric behavior in Y -doped HfO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> .