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Theoretical Investigation on Gas-Phase Reaction Mechanism of Cp2Mg in p-type doping process of Group III nitrides
Computational and Theoretical Chemistry ( IF 2.8 ) Pub Date : 2020-02-25 , DOI: 10.1016/j.comptc.2020.112763
Liu Tang , Hong Zhang , Yinmei Yuan

In this study, the reaction mechanism of p-type dopant Cp2Mg in the gas-phase of MOCVD was proposed and analyzed by quantum chemical calculations in accordance with density functional theory. It was reported that Cp2Mg primarily displayed two types of competing addition path and decomposition path. For adduct reaction path, complex Cp2Mg:NH3 or Cp2Mg:(NH3)2 would be formed in the low temperature range. The decomposition paths mainly includes the self-decomposition path, the hydrogenolysis path and the ammonolysis path. The self-decomposition path produces Mg atoms which are favorable for p-type doping, but the reaction energy barrier and decomposition temperature are high, which is theoretically difficult to proceed. However, the hydrogenolysis and the aminolysis paths involved with free radicals have lower reaction energy barriers and decomposition temperatures, thus, they are theoretically relatively easier to carry out, whereas the precursors MgH and MgNH2 produced are not conducive for p-type doping. Therefore, the presence of radicals in the gas phase was a “double-edged sword”. On the one hand, they exerted a positive auxiliary effect on Cp2Mg decomposition, significantly lowering the decomposition temperature of Cp2Mg. On the other hand, they reacted with Mg to form gas-phase complex, passivating Mg and hindering the effect of p-type doping.



中文翻译:

III族氮化物p型掺杂过程中Cp 2 Mg气相反应机理的理论研究

本研究提出了p型掺杂剂Cp 2 Mg在MOCVD气相中的反应机理,并根据密度泛函理论通过量子化学计算进行了分析。据报道,Cp 2 Mg主要表现出两种竞争性加成路径和分解路径。对于加合物反应路径,复杂的Cp 2 Mg:NH 3或Cp 2 Mg:(NH 32会在低温范围内形成。分解路径主要包括自分解路径,氢解路径和氨解路径。自分解路径产生的Mg原子有利于p型掺杂,但反应能垒和分解温度很高,理论上很难进行。然而,自由基所涉及的氢解和氨解路径具有较低的反应能垒和分解温度,因此,理论上它们较容易进行,而所产生的前体MgH和MgNH 2不利于p型掺杂。因此,气相中自由基的存在是一把“双刃剑”。一方面,它们对Cp 2发挥了积极的辅助作用Mg的分解,大大降低了Cp 2 Mg的分解温度。另一方面,它们与镁反应形成气相络合物,钝化了镁并阻碍了p型掺杂的作用。

更新日期:2020-02-25
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