The study of thermal silicon dioxide electrets formed by corona discharge and rapid-thermal annealing
The study of thermal silicon dioxide electrets formed by corona discharge and rapid-thermal annealing
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DOI：
10.1063/1.3559260
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发表时间：
2011-03-01
影响因子：
3.2
通讯作者：
McIntosh, Keith R.
中科院分区：
文献类型：
--
作者：
Kho, Teng C.;Baker-Finch, Simeon C.;McIntosh, Keith R.
二氧化硅(SiO_2)驻极体以两种方式钝化晶体硅(Si)的表面：(I)当退火和氢化时，SiO_2-Si界面具有低密度的界面态，几乎没有电子和空穴可以通过的复合能级；(Ii)驻极体的准永久电荷排斥相同极性的载流子，阻止大多数电荷到达SiO_2-Si界面，从而限制界面复合。在这项工作中，我们通过在氧化硅片表面沉积电晕电荷并对其进行快速热退火(RTA)来在硅上设计带电的热SiO_2驻极体。结果表明，表面电晕电荷通过RTA重新分布到氧化物内部。当充电量为80 S，温度为380℃，温度为60 S时，我们测得驻极体电荷密度为5×10(12)cm(-2)，超过此密度后，表面钝化不再有利。该工艺在1Omega-cm n型硅上获得了小于20 cm/S的表面复合速度，与用于高效硅太阳电池的最佳钝化方案相称。本文介绍了SiO_2驻极体的形成方法，分析了电荷密度与界面复合的关系，并用RTA评价了电荷的再分布。(C)2011年美国物理研究所。[DOI：10.1063/1.3559260]
A silicon dioxide (SiO2) electret passivates the surface of crystalline silicon (Si) in two ways: (i) when annealed and hydrogenated, the SiO2-Si interface has a low density of interface states, offering few energy levels through which electrons and holes can recombine; and (ii) the electret's quasipermanent charge repels carriers of the same polarity, preventing most from reaching the SiO2-Si interface and thereby limiting interface recombination. In this work, we engineer a charged thermal SiO2 electret on Si by depositing corona charge onto the surface of an oxide-coated Si wafer and subjecting the wafer to a rapid thermal anneal (RTA). We show that the surface-located corona charge is redistributed deeper into the oxide by the RTA. With 80 s of charging, and an RTA at 380 degrees C for 60 s, we measure an electret charge density of 5 x 10(12) cm(-2), above which no further benefit to surface passivation is attained. The procedure leads to a surface recombination velocity of less than 20 cm/s on 1 Omega-cm n-type Si, which is commensurate with the best passivation schemes employed on high-efficiency Si solar cells. In this paper, we introduce the method of SiO2 electret formation, analyze the relationship between charge density and interface recombination, and assess the redistribution of charge by the RTA. (C) 2011 American Institute of Physics. [doi:10.1063/1.3559260]