Effect of Al-doped ZnO or Sn-doped In₂O₃electrode on ferroelectric properties of (Pb,La)(Zr,Ti)O₃capacitors

Abstract

Using chemical solution deposition, we fabricated ferroelectric (Pb,La)(Zr,Ti)O3 (PLZT) capacitors with either Al-doped ZnO (AZO) or Sn-doped In2O3 (ITO) top electrodes. Then, the effects of a thin conductive AZO or ITO buffer layer between the Pt bottom electrode and PLZT thin film were investigated in combination with an AZO or ITO top electrode (AZO/PLZT/AZO/Pt and ITO/PLZT/ITO/Pt). The H2 degradation resistance of the AZO/PLZT/AZO/Pt and ITO/PLZT/ITO/Pt capacitors was improved. For AZO/PLZT/AZO/Pt capacitors with 10- and 20-nm-thick buffer layers, the H2 degradation resistance was 91 and 81%, respectively, compared with 42–70% without a buffer layer. The H2 degradation resistance of ITO/PLZT/ITO/Pt capacitors with a 28-nm-thick buffer layer was improved to 85% from 60–76% without a buffer layer. The time-of-flight secondary ion mass spectrometry depth profile indicated that AZO is the better H2 barrier after forming gas (3% H2/balance N2) annealing.

Ferroelectric properties of (Pb,La)(Zr,Ti)O3 capacitors employing Al-doped ZnO top electrodes prepared by pulsed laser deposition under different oxygen pressures

“…6) Hydrogen degradation results from the reductive chemical reaction of ferroelectric materials with hydrogen, caused by their catalytic effects. 7) Also, ferroelectric Pb(Zr,Ti)O 3 (PZT) capacitors fabricated on Pt show serious fatigue problems in which the oxygen vacancies play an important role. 8) Noble metal oxide electrodes such as PtO x , IrO 2 , and SrRuO 3 help control the density of oxygen vacancies at the ferroelectric interface, because they can provide oxygen to compensate vacancies in the ferroelectric thin film.…”

“…11) The use of Al-doped ZnO (AZO), Sn-doped In 2 O 3 , LaNiO 3 (LNO), and La x Sr 1−x CoO 3 material systems, which contain no noble metals, also has been considered to overcome these problems. 7,[12][13][14][15] Al is more commonly used as a dopant for ZnO than other Al-group metals (e.g., B, Ga, and In) because AZO thin films exhibit low electrical resistivity compared with undoped ZnO. [16][17][18] AZO has also attracted much attention because of its low cost, good optical and electrical properties, heat stability, non-toxicity, and high transparency.…”

Al:ZnO top electrodes deposited with various oxygen pressures for ferroelectric (Pb,La)(Zr,Ti)O 3 capacitors

“…However, FeRAM currently has a limited market, mainly due to cost and issues with integration [6]. Recently, the use of Al:ZnO (AZO), Sn:In 2 O 3 , LaNiO 3 , and La x Sr 1−x CoO 3 material systems has been considered to overcome these problems [7][8][9][10][11]. ZnO films exhibit low electrical resistivity (2-4 × 10 −4 Ω cm) with appropriate doping densities (using Al), and AZO films have been reported [12,13].…”

“…XRD and field emission SEM were used to investigate the crystalline structure and morphology [9]. Then, polarisation-voltage (P−V) hysteresis characteristics and hydrogen degradation resistance were evaluated by the same way reported previously [9]. Fig.…”

Fabrication of doped Pb(Zr,Ti)O 3 capacitors on Pt substrates with different orientations

“…A solution was spin-coated onto the Pt substrate to form capacitor structures. Details of the fabrication process have been reported previously [9][10][11].…”