磁控溅射制备Nb掺杂IZO薄膜光电学性能研究

Optical and Electronic Properties of Nb Doped Indium-zinc Oxide Films Grown by Magnetron Sputtering

通过磁控溅射方法制备一种新型薄膜晶体管有源层材料Nb掺杂的氧化铟锌(IZO)非晶薄膜(a-INZO)。运用XRD、光致发光、Hall测试等检测方法分析INZO薄膜微观结构、缺陷状态以及电学性能。光致发光结果表明,INZO相较于Ga掺杂的IZO(IGZO)具有更低的深能级缺陷密度。Hall效应测试结果表明,通过调节溅射过程中氧气流量可有效控制INZO薄膜载流子浓度,使之适合于制备薄膜晶体管(TFT)器件。INZO薄膜迁移率随载流子浓度的变化规律符合渗流传导模型,载流子浓度较低时,迁移率随载流子浓度增加而增加;载流子浓度较高时,迁移率下降,光学数据的分析表明其带尾态宽度较大,结构更无序。提高溅射基底温度可有效提高迁移率,但对薄膜无序度的改善并不明显。

Niobium doped indium-zinc oxide（INZO） film, as a new channel layer material for thin film transistors（TFTs）, was deposited on glass by co- sputtering targets of IZO and Nb2O5. The optical and electronic properties of the films were investigated by means of XRD, photo luminescence（PL） and Hall effect measurements. The PL results indicate that the density of deep sub-gap states in INZO films is lower than that of Ga doped IZO（IGZO）. The Hall measurement results show that the carrier concentration of INZO can be effectively controlled by the O2 flow rates and thereby the carrier concentration of INZO can meet the requirement for TFT application as a channel layer. The Hall mobility increases with the increasing carrier concentration, which can be well explained by the percolation model. Optical analysis of Urbach energy demonstrates that the poor mobility with high carrier concentration originates from the structural disorder due to overabundant oxygen vacancies. The films deposited on the substrate at250℃ exhibit higher mobility but more or less the same degree of structural disorder in comparision with that at 30 ℃.