Hoteroepitaxial growth of ferroelectric thin film on Si substrate by controlling the interface

(1)反应溅射制备的Si衬底上的YSZ外延膜在800℃的温度下冷却速率为0.1 ~ 1000K/s时，其C- v特性几乎没有变化。而当冷却速率为1 ~ 10 K/s时，薄膜的分解特性良好。(2)我们观察到，在等离子体辐射较强的Si上沉积的外延YSZ薄膜的C-V特性中离子漂移更强。(3)发现在460和470 oc下沉积的外延YSZ薄膜上的PZT薄膜是异质外延单斜（110）PZT薄膜。在300、325和3500℃条件下，单斜PZT膜的漏电流均小于1 × 10^<-7> A/cm^2。由于铁电性质，其C-V特性表现为磁滞回线。(4)在（100）YSZ外延层上获得了异质外延Ir薄膜。当沉积速率大于0.42 nm/min和大于1.2 nm/mm时，沉积的Ir薄膜的取向分别为（100）和（111），发现（100）外延Ir薄膜的表面结晶质量明显优于YSZ外延薄膜。(5)我们分别在600°C的外延（100）Ir薄膜和650°C的外延（111）Ir薄膜上获得了外延（100）和(i) PZT薄膜。(6)外延PZT薄膜的（001）取向度越强，晶体质量越好，剩余极化越大，漏电流越低。(7)我们发现在YSZ层和Si衬底之间的氧化硅层使得缓冲层的介电常数降低。通过控制Zr+Y金属膜沉积工艺，可以抑制氧化硅层的形成。

(1) We hardly observed the difference on the C-V characteristics of the epitaxial YSZ films on Si substrates deposited by reactive sputtering with the cooling rates of 0.1 to 1000K/s at 800ﾟC.However, the break down characteristics were good for the films produced with the cooling rates of 1 to 10 K/s.(2) We observed that the stronger ion drift in the C-V characteristics of the epitaxial YSZ films on Si deposited with heavier plasma radiation.(3) It was found that the PZT films on epitaxial YSZ films deposited at 460 and 470ﾟC were heteroepitaxial monoclinic (110) PZT films. The leakage current of the monoclinic PZT film step-annealed at 300, 325 and 3500 C was less than 1X10^<-7> A/cm^2. Its C-V characteristics showed the hysteresis loop due to the ferroelectric property.(4) We obtained the heteroepitaxial Ir films on epitaxial (100) YSZ layers. When the deposition rates were later than 0.42 nm/min and faster than 1.2 nm/mm, the orientation of the deposited Ir films were (100) and (111), respectively, It was found that the surface crystalline quality of the epitaxial (100) Ir film was much better than that of the epitaxial YSZ film.(5) We obtained the epitaxial (100) and (Ill) PZT films on the epitaxial (100) Ir film at 600ﾟC and the epitaxial (111) Ir film at 650ﾟC, respectively.(6) When the degree of the (001) orientation of the epitaxial PZT film became stronger and the crystalline quality became better, the remanent polarization became larger and the leakage current became lower.(7) We found that the Si oxide layer between the YSZ layer and the Si substrate made the dielectric constant of the buffer layer decrease. This Si oxide layer formation can be suppressed by controlling the Zr+Y metal film deposition process.