物理学报2016，Vol.65Issue(12)：128501-1-128501-10,10.DOI:10.7498/aps.65.128501
铟锌氧化物薄膜晶体管局域态分布的提取方法∗
Extraction of density of lo calized states in indium zinc oxide thin film transistor
摘要
Abstract
Density of localized states (DOS) over the band-gap determines the electrical and instability characteristics in the indium zinc oxide thin film transistor (IZO TFT). In order to propose an accurate extraction method for DOS in the bulk region, low frequency noise and multi-frequency capacitance voltage characteristics are measured and analyzed in this paper. Firstly, the relationship between surface potential and gate voltage is extracted based on subthreshold I-V characteristics. The extraction results show that the surface potential increases with the increase of gate voltage in the sub-threshold region. When the Fermi level is close to the bottom of conduction band, the increase of surface potential should be saturated. Secondly, drain current noise power spectral densities in the IZO TFTs under different operation modes are measured. Based on carrier number fluctuation mechanism, the flat-band voltage noise power spectral density is extracted and localized state near IZO/SiO2 interface is then calculated. By considering the emission and trapping processes of carriers between localized states, the distribution of bulk trap density in the band-gap is extracted based on low frequency noise measurement results. The experimental results show an exponential tail state distribution in the band-gap while NTA is about 3.42 × 1020 cm−3·eV−1 and TTA is about 135 K. Subsequently, contact resistances are then extracted by combining capacitance-voltage characteristics with I-V characteristics in the linear region. The extrinsic parasitic resistances at gate, source, drain are separated. By considering charges trapped in the localized states and free carriers, the distributions of deep states and tail states in the active layer of IZO TFT are extracted through multi-frequency capacitance-voltage characteristics. The experimental results also show an exponential deep state and tail state distribution in the band-gap while NDA is about 5.4 × 1015 cm−3·eV−1, TDA is about 711 K, NTA is about 1.99×1020 cm−3·eV−1, and TTA is about 183 K. The above two proposed extraction methods are compared and analyzed. The deviation between two extraction results may relate to the existence of neutral trap in the gate dielectric which is also an important source of low frequency noise in the IZO TFT.关键词
薄膜晶体管/变频电容-电压/低频噪声/缺陷态Key words
thin film transistor/multi-frequency capacitance-voltage/low frequency noise/density of localized state引用本文复制引用
王静,刘远,刘玉荣,吴为敬,罗心月,刘凯,李斌,恩云飞..铟锌氧化物薄膜晶体管局域态分布的提取方法∗[J].物理学报,2016,65(12):128501-1-128501-10,10.基金项目
国家自然科学基金(批准号:61574048,61574062,61204112)和广东省自然科学基金(批准号:2014A030313656,2015A030306002)资助的课题.@@@@* Project supported by the National Natural Science Foundation of China (Grant Nos.61574048,61574062,61204112) and the Natural Science Foundation of Guangdong Province, China (Grant Nos.2014A030313656,2015A030306002) （批准号:61574048,61574062,61204112）
