溅射气压对Ba_(0.5)Sr_(0.5)TiO_3薄膜变容管漏电特性影响研究

Effects of sputtering pressure on the leakage current characteristics of Ba_(0.5)Sr_(0.5)TiO_3 thin film varactors

在氧气和氩气的混合气体中,采用射频磁控溅射方法在蓝宝石基片上溅射生长了Ba0.5Sr0.5TiO3(BST)薄膜,使用微细加工工艺制备了BST薄膜变容管,研究了溅射气压对薄膜变容管漏电流特性的影响。结果表明在基片温度800℃,溅射气压2.0 Pa,氧氩分压比为3:17的条件下沉积的BST薄膜结构致密,表面平整,所制薄膜变容管具有较小漏电流,在较高外加电场强度(3.0×106V/cm)下其漏电流密度不超过1.3×10–4A/cm2,耐压可以达到120 V,调谐率约为53.7%。

Barium strontium titanate （BST） thin film were prepared on sapphire substrates via radio frequency（RF） magnetron sputtering in the mixed gases of oxygen and argon, and BST thin film varactors were fabricated by microfabrication techniques, the effects of sputtering pressure on the leakage current characteristics of the BST thin film varactors were investigated. The results show that the dense and fiat BST thin films are formed and the varactor with lower leakage current is achieved at substrate temperature of 800 ℃with sputtering pressure of 2.0 Pa and volume flow rateψ（O2：Ar） of 3：17, the leakage current density of the prepared varactor is smaller than 1.3× 10^4 A/cm2 at a high DC bias filed strength of 3.0× 10^6 V/cm. The tunability is 53.7% and the operating voltage is up to 120 V for this varactor.