Epitaxial Stress‐Free Growth of High Crystallinity Ferroelectric PbZr_0.52Ti_0.48O₃ on GaN/AlGaN/Si(111) Substrate

Abstract

COMMUNICATION (1 of 8)Integration of complex oxide materials with traditional electronic materials such as silicon (Si) and III-V semiconductors has attracted tremendous attention and efforts are being spent to overcome the growth challenges due to oxidation of the semiconducting materials and/or large lattice mismatch between those. [1][2][3][4][5][6][7][8][9] A breakthrough occurred for the growth of strontium-titanate (SrTiO 3 or STO) on Si, where, by introducing a 1/2 monolayer strontium (Sr) as a template, the oxidation of Si is prevented and renders the epitaxial growth of STO on Si by molecular beam epitaxy (MBE) possible. [1,2] Another strategy is to deposit an yttria-stabilized zirconia (YSZ) buffer layer to remove Due to its physical properties gallium-nitride (GaN) is gaining a lot of attention as an emerging semiconductor material in the field of high-power and high-frequency electronics applications. Therefore, the improvement in the performance and/or perhaps even extension in functionality of GaN based devices would be highly desirable. The integration of ferroelectric materials such as lead-zirconate-titanate (PbZr x Ti 1-x O 3 ) with GaN has a strong potential to offer such an improvement. However, the large lattice mismatch between PZT and GaN makes the epitaxial growth of Pb(Zr 1-x Ti x )O 3 on GaN a formidable challenge. This work discusses a novel strain relaxation mechanism observed when MgO is used as a buffer layer, with thicknesses down to a single unit cell, inducing epitaxial growth of high crystallinity Pb(Zr 0.52 Ti 0.48 ) O 3 (PZT) thin films. The epitaxial PZT films exhibit good ferroelectric properties, showing great promise for future GaN device applications.

Epitaxial Oxides on Semiconductors: From Fundamentals to New Devices

“…c) In‐plane P – E loops of PZT/MgO/GaN structures, where the different curves represent different MgO buffer thicknesses. Reproduced with permission . Copyright 2018, Wiley‐VCH.…”

“…More recently, Elibol et al employed thick (tens of nm) rutile TiO 2 layers as templates for the growth of ferroelectric Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) using PLD, which yielded films with an in‐plane polarization. A follow‐up work by this group replaced the thick TiO 2 buffer layer with MgO, which also yielded ferroelectric films with an in‐plane polarization (Figure c).…”

Stabilization of phase-pure rhombohedral HfZrO4 in pulsed laser deposited thin films

“…by increasing the threshold voltage or the ON/OFF ratio) of such transistors. [1][2][3] However the integration of such ferroelectric materials (usually perovskites [2,[4][5][6][7] ) on GaN is challenging due to the large lattice mismatch between the two structures and a buffer layer, such as MgO, [2,7] Al2O3, [6] or TiO2, [8] is commonly used to allow for the mismatch. Direct integration of a fully epitaxial ferroelectric material on GaN is the promise of further improvement for such devices.…”

Designing functional ferroelectric interfaces from first-principles: dipoles and band bending at oxide heterojunctions

“…Ferroelectric interfaces are key elements for the functionality of these heterostructures. Their underlying phenomenology is determined by the chemistry of the specific materials, their thickness, as well as the design and quality of interfaces [39][40][41][42][43]. At the interface with a ferroelectric the polar distortions are perturbed, the local strain, bonding across the interface and the built-in electric field promote charge transfers and space charge build-up.…”