Large piezoelectricity on Si from highly (001)-oriented PZT thick films via a CMOS-compatible sputtering/RTP process

Boosting energy storage performance of low-temperature sputtered CaBi2Nb2O9 thin film capacitors via rapid thermal annealing

“…The CBNO A350 films were poorly crystallized, close to an amorphous state. After the RTA process, the overall crystalline quality of the as-grown film has been improved, mostly from growth of the (1, 1, 2n+1) grains driven by an interface energy [25,26,28]. Compared with those of the perovskite Pb(Zr , Ti)O 3 thin films [28], recrystallization and grain growth of the CBNO film during an RTA process are much more limited because of its strong anisotropic lattice.…”

“…After the RTA process, the overall crystalline quality of the as-grown film has been improved, mostly from growth of the (1, 1, 2n+1) grains driven by an interface energy [25,26,28]. Compared with those of the perovskite Pb(Zr , Ti)O 3 thin films [28], recrystallization and grain growth of the CBNO film during an RTA process are much more limited because of its strong anisotropic lattice. The CBNO 350-RTA film showed a preferred (115)-orientation, which is about 56° tilted away from the [100]/[010] polar axis (with a theoretical P s  24.4 C/cm 2 ) [23].…”

“…Specifically, under the same electric field of 1 MV/cm, the energy performance of the CBNO 350-RTA film (W rec  10.4 J/cm 3 and   93%) was much better than that of the CBNO A700 (W rec  6.4 J/cm 3 and   50.4%). In addition, a longer exposure to the high processing temperature of 700 ℃ helped generate more defects in the CBNO A700 film [28,31], leading to its lower breakdown strength/maximum applicable field, and hence contributes to a lower energy storage capability. The higher breakdown field of the CBNO 350-RTA film, as compared to that of CBNO A350 , is most likely due to the rapid thermal annealing process, which helped improve crystallinity of the film as well as reduce the number and volume ratio of poorly crystallized grain boundaries with many associated defects [32,33].…”

“…Such a low-temperature deposition process facilitates nucleation of the (115) grains, which have a low activation energy and a high dielectric constant [20,27]. Then the samples were annealed in a rapid thermal annealing furnace at 700 ℃ for 15 min, which promotes a limited growth of the (115) grains and improves the overall crystalline quality of the as-grown film [25,26,28]. Compared with a single-step, high-temperature sputtering growth at 700 ℃, this two-step process not only reduces the thermal budget, but also decreases the average grain size.…”

“…From Figs.1(b) and 1(d), a smooth surface and a dense film morphology, as well as a nanograin structure, can be observed in both the CBNO A350 and CBNO 350-RTA films. The uniform and small grain size of the CBNO 350-RTA film is a natural consequence of the RTA process, which promotes a limited grain growth dictated by minimization of the interface energy[25,28]. A slim P-E hysteresis, a high breakdown field, and a low leakage current are expected for the CBNO 350-RTA film from its dense and nanograined microstructure.Figures…”