Enhanced electrical properties of In-Ga-Sn-O thin films at low-temperature annealing
Enhanced electrical properties of In-Ga-Sn-O thin films at low-temperature annealing
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DOI：
10.1016/j.ceramint.2021.12.183
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发表时间：
2021-12
影响因子：
5.2
通讯作者：
Changjin Oh;H. Jung;So Hee Park;Bo Sung Kim
中科院分区：
文献类型：
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作者：
Changjin Oh;H. Jung;So Hee Park;Bo Sung Kim
研究了射频磁控溅射制备的In-Ga-SnO(IGTO)薄膜的电学和光学性质。虽然IGTO薄膜在500℃以下进行热处理后仍然是非晶相，但霍尔测量表明，退火温度对IGTO薄膜的电学性能有很大影响。研究了从沉积状态到500℃的不同温度范围内的样品，发现在200℃下热处理的薄膜具有最好的电性能，其电导率为229.31Ω−1 cm−1，霍尔迁移率为36.89cm2V−1s−1，载流子浓度为3.85t×1019 cm−3。用X射线光电子能谱分析了氧相关缺陷的比例以及薄膜中Sn2+和Sn4+离子的百分比随退火温度的变化，以确定低温下IGTO薄膜性能优异的原因。在200℃热处理的IGTO薄膜中，Sn4+离子作为施主缺陷的比例很高，而羟基作为电子陷阱的比例比沉积时的薄膜明显减少。由紫外-可见光谱得到的IGTO薄膜的光学带隙为3.38-3.47 eV。在200℃下热处理的IGTO薄膜的最大带隙为3.47 eV，这可能是由于导带中载流子浓度的增加导致了费米能级的增加。这些光谱结果与IGTO薄膜随退火温度变化的电学性质很好地匹配。在200℃下热处理的IGTO薄膜具有优异的电学性能，这在很大程度上是由于除氧空位外，锡施主的作用，导致自由载流子显著增加。温度。
Electrical and optical properties of In-Ga-Sn-O (IGTO) thin films deposited by radio-frequency magnetron sputtering were investigated according to annealing temperatures. While IGTO films remained an amorphous phase even after a heat treatment at temperature up to 500 °C, Hall measurements showed that annealing temperature had a significant impact on electrical properties of IGTO thin films. After investigating a wide range of annealing temperatures for samples from as-deposited state to 500 °C, IGTO film annealed at 200 °C exhibited the best electrical performance with a conductivity of 229.31 Ω−1cm−1, a Hall mobility of 36.89 cm2V−1s−1, and a carrier concentration of 3.85 × 1019cm−3. Changes in proportions of oxygen-related defects and percentages of Sn2+and Sn4+ions within IGTO films according to annealing temperatures were analyzed with X-ray photoelectron spectroscopy to determine the cause of the superb performance of IGTO at a low temperature. In IGTO films annealed at 200 °C, Sn4+ions acting as donor defects accounted for a high percentage, whereas hydroxyl groups working as electron traps showed a significantly reduced percentage compared to the as-deposited film. Optical band gaps of IGTO films obtained from UV–visible spectrum were 3.38–3.47 eV. The largest band gap value of 3.47 eV for the IGTO film annealed at 200 °C could be attributed to an increase in Fermi-level due to an increase of carrier concentration in the conduction band. These spectroscopic results well matched with electrical properties of IGTO films according to annealing temperatures. Excellent electrical properties of IGTO thin films annealed at 200 °C could be largely due to Sn donors besides oxygen vacancies, resulting in a significant increase in free carriers despite a low annealing. temperature.