Role of Gas Doping Sequence in Surface Reactions and Dopant Incorporation during Atomic Layer Deposition of Al-Doped ZnO
Role of Gas Doping Sequence in Surface Reactions and Dopant Incorporation during Atomic Layer Deposition of Al-Doped ZnO
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DOI：
10.1021/cm901404p
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发表时间：
2009-12-08
影响因子：
8.6
通讯作者：
Parsons, Gregory N.
中科院分区：
文献类型：
--
作者：
Na, Jeong-Seok;Peng, Qing;Parsons, Gregory N.
采用原位石英晶体微天平和电导分析研究了原子层沉积（ALD）过程中ZnO薄膜中铝的掺入。在ZnO：Al ALD期间Zn和Al物种之间的化学相互作用取决于金属前体暴露的顺序。将生长的ZnO表面暴露于三甲基铝（TMA）阻碍随后的类似于4个ZnO单层的生长。然而，相互作用的程度可以通过在二乙基锌步骤之后立即进行TMA暴露来降低，而没有中间水暴露步骤，这与Zn和All物质的增加的表面混合一致。红外光谱分析表明，重铝掺杂ZnO的功能与无定形ZnAl2O4键合单元的存在一致。对于更轻掺杂的膜，质谱深度剖析证实了不均匀的铝分布，即使在500摄氏度退火后。在生长过程中测得的薄膜电导显示出复杂的趋势，是高度可重复的多个掺杂周期，和原位电导值是一致的沉积后电流与电压特性。结果被理解的表面物种的相对键能，和预期的掺杂剂原子掺入的反应途径。
Aluminum incorporation into ZnO films during atomic layer deposition (ALD) is investigated using in situ quartz crystal microbalance and electrical conductance analysis. Chemical interactions between Zn and Al species during ZnO:AI ALD depend on the order of metal precursor exposure. Exposing the growing ZnO surface to trimethyl aluminum (TMA) impedes the subsequent similar to 4 monolayers of ZnO growth. However, the extent of interaction can be reduced by performing the TMA exposure immediately following a diethyl zinc step, without an intermediate water exposure step, consistent with increased surface mixing of Zn and All species. Infrared spectroscopy analysis of heavily aluminum doped ZnO shows features consistent with the presence of amorphous ZnAl2O4 bonding units. For more lightly doped films, mass spectroscopic depth profiling confirms nonuniform aluminum distribution, even after annealing at 500 degrees C. Film conductance measured during growth shows complex trends that are highly repeatable over multiple doping cycles, and values for in situ conductance are consistent with postdeposition Current vs. voltage characterization. Results are understood in terms of relative bonding energies Of Surface species, and expected reaction pathways for dopant atom incorporation.