Electrical Properties of P-N Contact of Oxide Semiconductor Fabricated via Chemical Solution Deposition

以四异丙醇钛、醋酸锌、醋酸镍、醋酸钴为原料，加入二乙醇胺作为金属离子改性剂，制备了异丙醇溶液。浸渍、烘干、600℃焙烧可得到均匀、薄的金属氧化物薄膜。生成的薄膜是透明的。在玻璃衬底(Corning#7059)上溅射ITO(TiN掺杂In_2O_3)制备的p型NiO和n型TiO_2复合薄膜具有良好的整流性能和透明性。这种整流性能在300℃的高温下保持不变。利用氧化物半导体的宽禁带特性作为p-n接触多层膜，考察了其他金属离子稳定剂α-羟基酮的性能。这些酮的沸点比乙醇胺低。乙酸乙酯(CH_3-CO-CHOH-CH_3)和丙醇(CH_3-CO-CH_2OH)的加入使钛和锌的稳定溶液得以制备。特别是通过α-羟基酮和一乙醇胺的共加成可以得到钛的水溶液，用乙酸乙酯和一乙醇胺共加成的氧化锌薄膜在玻璃基片上是c取向的。这种c取向的氧化锌薄膜具有较低的电阻率，比随机取向的薄膜低约2个数量级。在SiO_2/Si衬底上沉积了氧化锌薄膜，在氧化锌表面真空蒸发两个金电极，制成漏极和源极。由此制备了底栅型氧化锌薄膜晶体管(TFT)。这种氧化锌薄膜晶体管在200℃的高温下表现出增强型薄膜晶体管的特性。

Titanium tetraisopropoxide, zinc acetate, nickel acetate and cobalt acetate were used as raw reagents to prepare isopropanol solutions with addition of diethanolamine as a metal ion modifier. The uniform and thin metal oxide films could be obtained by a dip-coating, drying, and firing at 600 ℃. The resultant films were transparent. The multi-coating film of p-type NiO and n-type TiO_2 on glass substrate (Corning #7059) sputtered with ITO (tin doped In_2O_3) exhibited a rectifying property and transparent. This rectifying property was maintained at high temperature as 300 ℃. The superior characteristics of oxide semiconductor, i.e., wide band gap character, was utilized as p-n contact multi-layered film.The other metal ion stabilizers, α-hydroxyketones, were examined. These ketones characterize their lower boiling point than ethanolamines. The addition of acetin (CH_3-CO-CHOH-CH_3) and acetol (CH_3-CO-CH_2OH) enable to prepare the stable solutions of Ti and Zn. Especially, an aqueous solution of Ti could be prepared by the co-addition of α-hydroxyketones and monoethanolamine.Zinc oxide film prepared using co-addition of acetoin and monoethanolamine was c-oriented on the glass substrate. This c-oriented ZnO film exhibited low electrical resistivity, about 2 orders of magnitude lower than that of the random oriented film. The ZnO film was deposited on a SiO_2/Si wafer and two gold electrodes were vacuum evaporated on the ZnO surface to make drain and source electrodes. The bottom gate type ZnO thin film transistor (TFT) was thus fabricated. This ZnO TFT exhibited a character of a enhancement type thin film transistor at high temperature of 200 ℃.