INVESTIGATION OF ENERGY BAND DIAGRAM OF ORGANIC ULTRA-THIN FILM BY SIMULTANEOUS MEASUREMENT OF TUNNELING AND DISPLACEMENT CURRENTS

本研究的目的是通过同时测量隧道电流和位移电流来澄清有机超薄膜的能带图。本次调查是根据研究者提出的隧道和位移电流同时测量方法的想法进行的。首先，通过在半导体表面振动扫描探头，成功地同时测量了半导体表面的隧穿电流和位移电流，分析了理论位移电流随电压的变化曲线，并与实验结果进行了拟合。理论位移电流曲线与实测结果吻合较好。然后，研究人员开发了半导体的局部载流子浓度和俘获表面电荷密度的测定方法。为了弄清有机超薄膜的传导电流与空间电荷之间的关系，将聚酰亚胺薄膜在热氧化硅衬底上进行了更多的自旋涂覆。测量了厚度为3 nm的聚酰亚胺/厚度为1 nm的SiO2 /硅结构的隧穿电流和位移电流。用位移电流曲线测定了聚酰亚胺薄膜中的空间电荷密度。用差分隧道电流谱法估计了态依赖的密度，发现它起源于硅。结果表明，聚酰亚胺薄膜具有空间电荷绝缘体的作用，可以用该方法测定导电超薄有机薄膜的态密度和空间电荷。主要研究结果如下：(1)利用扫描振动探针测量位移电流-电压曲线中的半导体局部载流子浓度。(2)利用扫描振动探头对位移和隧道电流进行波形分离。(3)利用扫描振动探针从位移电流-电压曲线测定半导体表面空间电荷密度。(4)利用扫描振动探针测量聚酰亚胺/ SiO2 /硅结构的扫描隧道光谱。少

The purpose of this investigation was to clarify the energy band diagram of organic ultra-thin film by simultaneous measurement of tunneling and displacement currents. This investigation has been carried out on the basis of the idea of simultaneous measuring method of tunneling and displacement currents proposed by the investigator. As a first step, the investigator has succeeded to measure the tunneling and displacement currents on semiconductor simultaneously by vibrating the scanning probe to the semiconductor surface The theoretical displacement current versus voltage curve was analyzed and was fitted to the experimental results., The theoretical displacement current curves are in good agreement with the measurement. Then, the investigator has developed the determination methods of local carrier concentration and trapped surface charge density of semiconductor. To clarify the relationship between the conduction current and space charge of organic ultra-thin film, polyimide film was … More spin-coated onto the thermally oxidized silicon substrate. The tunneling and displacement current of polyimide (3 nm in thickness) / SiO2 (1 nm in thickness) / silicon structure have been measured. The space charge density in polyimide film has been determined by displacement current curves. The density of state dependence was estimated by differential tunneling current spectroscopy and was found to be originated to the silicon. These results indicate that the polyimide film act as a insulator with space charges and that the density of states and space charges of conductive ultra-thin organic films can be determined by this method. The results were summarized as follows: (1) Measurement of semiconductor local carrier concentration from displacement current-voltage curves with a scanning vibrating probe. (2) Wave form separation of displacement and tunneling currents using a scanning vibrating probe. (3) Determination of surface space charge density on semiconductor from displacement current-voltage curve using a scanning vibrating probe. (4) Measurements of scanning tunneling spectroscopy of polyimide / SiO2 / silicon structure by using the scanning vibrating probe. Less