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

以四异丙醇钛、乙酸锌、乙酸镍和乙酸钴为原料，加入二乙醇胺作为金属离子改性剂，制备异丙醇溶液。通过浸涂、干燥和600 ℃焙烧可获得均匀、薄的金属氧化物薄膜。所得膜是透明的。用ITO（掺锡In_2O_3）溅射法在玻璃（Corning #7059）上制备的p型NiO和n型TiO_2多层膜具有整流性和透明性。在300 ℃的高温下仍能保持这种整流特性。氧化物半导体的上级特性，即，宽禁带特性，用作p-n接触多层膜，并对其它金属离子稳定剂α-羟基酮进行了研究。这些酮的特征是它们的沸点比乙醇胺低。加入乙酸乙酯（CH_3-CO-CHOH-CH_3）和丙酮醇（CH_3-CO-CH_2 OH）可制得稳定的钛、锌溶液。特别是α-羟基酮和单乙醇胺的共加成可以制备出Ti的水溶液，乙偶姻和单乙醇胺的共加成制备的ZnO薄膜在玻璃基底上呈c向取向。这种c取向的ZnO膜表现出低电阻率，比无规取向的膜低约2个数量级。在SiO_2/Si基片上沉积ZnO薄膜，并在ZnO表面真空蒸镀两个金电极制成漏、源电极。由此制造底栅型ZnO薄膜晶体管（TFT）。这种ZnO TFT在200 ℃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 ℃.