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从高频电容电压特性测试中发现的隧道电容溢出现象出发,研究了具有超薄钝化层的半导体-绝缘体-半导体(semiconductor-insulator-semiconductor SIS)异质结器件界面处独特的电荷存储特性.从SIS 1 MHz频率下的CV特性可知,当外加偏压小于V_T(voltage tunneling)时,SIS界面处于耗尽状态,而当外加栅压超过V_T之后,SIS的高频电容将远超仪器量程趋于无穷大,可概括称为隧道电容溢出现象.从SIS的XPS(X-ray photoemission spectroscopy)深度剖析结果可知,具有不同厚度的ITO(indium tin oxide)的SIS器件界面钝化层所含元素组分并无差别.但从TEM(transparent electron microscope)的结果来看,钝化层厚度随ITO的增加而增加,分析表明不同ITO厚度的SIS所对应V_T值不同的主要原因是由于钝化层厚度的不同.通过对实验结果的分析,本文给出了隧道电容溢出现象的载流子输运的能带模型.结果表明,隧道电容溢出是由于超薄钝化层无法使大量电子在界面处积累所致.且同一器件隧道电容溢出现象是可重复的,不会对器件带来物理损伤,这是采用直接磁控溅射工艺制备SIS异质结太阳电池稳定性的体现.
Based on the phenomenon of tunneling capacitance leakage observed in the high-frequency capacitor voltage characteristics test, the unique charge-storage characteristics at the interface of a semiconductor-insulator-semiconductor (SIS) heterojunction device with an ultrathin passivation layer are investigated. From the CV characteristics of SIS 1 MHz, it can be seen that the SIS interface is depleted when the applied bias voltage is less than V_T (voltage tunneling). When the applied gate voltage exceeds V_T, the high frequency capacitance of SIS will far exceed the instrumentation range In infinite, it can be broadly described as tunneling capacitor overflow phenomenon.From the SIS XPS (X-ray photoemission spectroscopy) depth analysis results show that the elemental components contained in the passivation layer of the interface of the SIS device with different thickness of indium tin oxide (ITO) However, from the results of TEM (transparent electron microscope), the thickness of the passivation layer increases with the increase of ITO. The analysis shows that the main reason for the different V_T values of SIS with different ITO thickness is that the passivation layer thickness Different.Through the analysis of the experimental results, this paper gives the band model of tunneling capacitor overflow phenomenon carrier transport.The results show that the tunnel capacitor overflow is due to the ultra-thin Layer can not make a large number of electrons accumulated at the interface caused by the same device and the tunnel capacitor overflow phenomenon is repeatable, will not cause physical damage to the device, which is prepared by direct magnetron sputtering SIS heterojunction solar cell The embodiment of stability.