Insertion of Dielectric Interlayer: A New Approach to Enhance Energy Storage in HfxZr1-xO2 Capacitors

Abstract

In this letter, we demonstrate an effective way to enrich the performance of HfxZr1-x O-2 (HZO) energy storage capacitors (ESCs) by inserting Al2O3 dielectric interlayer (DIL) in the middle of HZO in TiN/HZO/TiN structure. The impact of DIL (1 angstrom, 5 angstrom and 10 angstrom) is investigated in three different HZO compositions [1:1, 1:2 and 1:3]. Irrespective of HZO composition, insertion of DIL at critical thickness enhances the energy storage density (ESD) and efficiency of the ESCs. Grazing incident X-ray diffractometer (GIXRD) analysis reveals that Al2O3 DIL controls the grain size of the HZO films resulting in lower energy dissipation by controlling the linearity of the hysteresis loop. At 4.5 MV/cm, the best ESD similar to 55 J/cm(3) with similar to 68% efficiency is achieved for HZO [1:2] capacitors at a critical Al2O3 thickness of 1 angstrom which is similar to 35% and similar to 55% enhanced as compared to that without DIL [similar to 41 J/cm(3), similar to 44%]. The best efficiency of similar to 88% is achieved [ESD similar to 26 J/cm(3)] for HZO [1:3] capacitors at a critical DIL thickness of 10 angstrom. The HZO [1:2] ESC with 1 angstrom DIL displays robust thermal stability in 25 degrees C to 200 degrees C temperature range. Moreover, the aforesaid ESCs demonstrate excellent electrical stability even after 10(9) times of electric field cycling. Highest ESD of similar to 70 J/cm(3) at similar to 50% efficiency is achieved for the same ESC when operated at 6.0 MV/cm. The results obtained herein provide a new strategy to achieve high performance ESCs and can be of significant scientific importance.