臨場監控雷射鍍膜法合成高介電常數薄膜電性、光性、微波特性研究

Abstract

本研究利用脈衝雷射鍍膜法(Pulsed Laser Deposition, PLD)合成PBZNZT x(0.94Pb(Zn1/3Nb2/3)O3+0.06BaTiO3)+(1–x)((1–y)PbZrO3+ yPbTiO3)( x=0.6, y=0.52 )薄膜。首先利用光多頻分析儀亦即可見光發射光譜儀(Optical Multichannel Analyzer, OMA, i.e., Optical Emission Spectroscope, OES)臨場監控並擷取分析靶材的電漿物種發射光譜，俾了解品管PLD適當的鍍膜參數條件，据以獲得BMT當緩衝層，在鍍膜溫度T= 400 ℃，雷射能量通量密度E= 1.50 J/cm2，雷射鍍膜重覆率R.R.= 5 Hz，氧分壓PO2 (PBZNZT)=0.50 mbar、PO2 (BMT)=0.90 mbar，PBZNZT、BMT靶材分別與基板間距為4.5 cm、4.0 cm，鍍膜時間t=30 min (PBZNZT)、15 s(BMT)，成功鍍得鈣鈦礦結構PBZNZT/BMT/MgO薄膜。再進一步量測分析所有薄膜的電性、光性、微波特性。 電性方面，雷射鍍PBZNZT薄膜的最佳矯頑電場Ec 值約522.32 kV/cm，最佳殘留電極化Pr值約25.99 C/cm2，且薄膜在頻率2 kHz的最佳低頻介電常數(εr) =737。 光性方面，PBZNZT/BMT/MgO薄膜晶粒大小均勻，約在50–100 nm，膜厚(d) =2193.37 nm，能隙(Eg)=0.85 eV，折射率(n)=1.9020，吸收係數(k)=0.00428 nm－1，最佳光頻介電常數(εr) =3.6153。 微波特性方面，PBZNZT/BMT/MgO薄膜的最佳微波介電常數(εr)約177.7，微波品質因子(Q)約10,080。 藉雷射鍍膜法研製具高介電常數PBZNZT薄膜，除可提供相關學術研究參考外，並可促成高介電常數薄膜之輕薄短小元件應用早日來臨。In this study, the PBZNZT [x(0.94Pb(Zn1/3Nb2/3)O3+0.06BaTiO3) +(1–x)((1–y)PbZrO3+yPbTiO3)( x=0.6, y=0.52 )] thin films have been synthesized by using pulsed laser deposition (PLD) technique. In order to understand and control the optimum PLD parameters, Optical Multichannel Analyzer (OMA) i.e., Optical Emission Spectroscope (OES) was firstly used to in-situ diagnostically take and analyze the optical emitted spectra of plasma species ablated from targets. Thus the as-deposited PBZNZT/BMT/MgO films with perovskite structure were successfully grown, using following PLD parameters: BMT [Ba(Mg1/3Ta2/3)O3] buffer layer, deposition temperature T= 400 ℃, laser fluence E= 1.50 J/cm2, PLD repetition rate R.R.= 5 Hz, oxygen pressure PO2 (PBZNZT)=0.50 mbar, PO2 (BMT)=0.90 mbar, distances between targets and substrates 4.5 cm(PBZNZT) and 4.0 cm(BMT), deposition time t (PBZNZT)=30 min and t (BMT)=15 s. The electrical, optical and microwave properties of the films were further measured and investigated. In electrical properties, pulsed laser deposited PBZNZT films have the optimized values of coercive electric field (Ec) = 522.32 kV/cm and remanent electric polarization (Pr) = 25.99 C/cm2, respectively. The maximum value of dielectric constant is about 737. In optical characteristics, PBZNZT/BMT/MgO films possess uniformly distributed grain sizes=50–100 nm, film thickness (d) =2193.37 nm, energy gap (Eg) =0.85 eV, index of refraction (n) =1.9020, optical absorption coefficient (k) =0.00428 nm－1. The optical dielectric constant (εr) =3.6153. In microwave properties, PBZNZT/BMT/MgO films have optimized dielectric constant (εr) and quality factor (Q) respectively around 177.7 and 10,080. Through pulsed laser deposition method, the fabricated PBZNZT thin films not only can be used to assist the related academic research, but also can be utilized to promote the light-thin-short-small device applications.