Field-effect passivation of the SiO2-Si interface
Field-effect passivation of the SiO2-Si interface
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DOI：
10.1063/1.370784
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发表时间：
1999-07-01
影响因子：
3.2
通讯作者：
Warta, W
中科院分区：
文献类型：
--
作者：
Glunz, SW;Biro, D;Warta, W
通过在太阳电池和寿命测试结构的氧化层上沉积电晕电荷，实验研究了硅上热氧化物界面的场效应钝化。通过在前向氧化物上沉积正或负电晕电荷，后接触交叉型太阳电池的开路电压可分别提高+12 mV或降低-34 mV。在不同注入能级和不同电荷密度的载流子寿命测试结构上，利用微波探测的光导衰变和俄歇限体寿命的新表达式，确定了有效表面复合速度S-Ef。在热氧化层厚度为105 nm的1欧姆p型硅片上，S效应可以在24 cm/S到538 cm/S之间变化。将测量结果与用于计算表面复合的分析模型的理论预测进行了比较。计算中使用了俘获截面和界面陷阱密度的测量值。与强负电荷密度相比，该模型预测了强正电荷密度的最佳钝化。这是由于电子和空穴的俘获截面的不对称性造成的。这一预测与S-伊夫值很好地吻合。然而，对于1欧姆厘米的p型硅，在实验中无法得到远低于1 cm/S的S-Eff值。这种差异可以用导致电势波动和额外损耗电流的不均匀电荷分布来解释。用一种新的扩展的分析模型计算S-Eff，可以定量地描述测量的S-Eff值。(C)1999年美国物理研究所。[S0021-8979(99)09113-6]。
The field-effect passivation of the interface of thermal oxides on silicon is experimentally investigated by depositing corona charges on the oxide of solar cells and of lifetime test structures. The open circuit voltage of solar cells with interdigitated rear contacts can be increased by +12 mV or decreased by -34 mV, respectively, by depositing positive or negative corona charges on top of the front oxide. The resulting effective surface recombination velocity, S-eff, is determined on carrier lifetime test structures for different injection levels and charge densities using microwave-detected photoconductance decay and a new expression for the Auger-limited bulk lifetime. S-eff can be varied between 24 cm/s and 538 cm/s on a 1 Omega cm p-type wafer with a thermal oxide of 105 nm thickness. The measurements are compared with theoretical predictions of an analytical model for the calculation of the surface recombination. Measured values for the capture cross sections and interface trap densities are used for the calculation. The model predicts an optimum passivation for strong positive compared to strong negative charge densities. This is due to the asymmetry of the capture cross sections for electrons and holes. This prediction is in very good agreement with the measured S-eff values. However, the predicted S-eff values of well below 1 cm/s for 1 Omega cm p-type silicon cannot be achieved in the experiment. This discrepancy can be explained by an inhomogeneous charge distribution resulting in potential fluctuations and additional loss currents. With a new extended analytical model for the calculation of S-eff the measured S-eff values can be described quantitatively. (C) 1999 American Institute of Physics. [S0021-8979(99)09113-6].