Abstract We report a systematic theoretical investigation on the activation mechanism of near-infrared In0.53Ga0.47As photocathodes. Adsorption energies, dipole moments, work functions, density of states, band structures and electron affinity of Cs/O co-adsorption on (001) surface of In0.53Ga0.47As photocathodes are investigated. First-principles calculation results indicate that the structural stability is greatly enhanced when oxygen atoms adsorb on the Cs-covered surface. The incorporation of oxygen atom helps lower the work function further to achieve the true NEA state. Moreover, two adatom-induced surface dipoles, namely [Csn+-In0.53Ga0.47Asn−] and [Cs+-O2--Cs+], are also adopted to explain the relationship between the adatoms and the substrate. The HOMO and LUMO levels can further move downward and the band bending region is enlarged after Cs/O co-activation. Meanwhile, new energy bands appear in the deep valence band due to the joint effect of Cs 5s, Cs 5p, O 2s and O 2p state electrons. Finally, Cs/O activation experiments are carried out and the photocurrent curves during activation procedure are recorded. The change of photocurrent is closely related to the work function variation, which affects the photoemission of the photocathodes. In order to clearly show the electron affinity, the variation of surface barrier height of InGaAs photocathodes with Cs/O adlayer is also given.

中文翻译：

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近红外In0.53Ga0.47As光电阴极Cs/O活化过程研究

摘要 我们对近红外 In0.53Ga0.47As 光电阴极的激活机制进行了系统的理论研究。研究了Cs/O共吸附在In0.53Ga0.47As光电阴极(001)表面的吸附能、偶极矩、功函数、态密度、能带结构和电子亲和力。第一性原理计算结果表明，当氧原子吸附在Cs覆盖的表面时，结构稳定性大大增强。氧原子的掺入有助于进一步降低功函数以实现真正的 NEA 状态。此外，还采用了两个吸附原子诱导的表面偶极子，即[Csn+-In0.53Ga0.47Asn-]和[Cs+-O2--Cs+]来解释吸附原子与衬底之间的关系。Cs/O 共激活后 HOMO 和 LUMO 能级可以进一步向下移动，带弯曲区域扩大。同时，由于Cs 5s、Cs 5p、O 2s 和O 2p 态电子的共同作用，新的能带出现在深价带中。最后，进行了 Cs/O 活化实验并记录了活化过程中的光电流曲线。光电流的变化与功函数变化密切相关，影响光电阴极的光电发射。为了清楚地显示电子亲和势，还给出了具有 Cs/O 吸附层的 InGaAs 光电阴极的表面势垒高度的变化。进行了 Cs/O 激活实验并记录了激活过程中的光电流曲线。光电流的变化与功函数变化密切相关，影响光电阴极的光电发射。为了清楚地显示电子亲和势，还给出了具有 Cs/O 吸附层的 InGaAs 光电阴极的表面势垒高度的变化。进行了 Cs/O 激活实验并记录了激活过程中的光电流曲线。光电流的变化与功函数变化密切相关，影响光电阴极的光电发射。为了清楚地显示电子亲和势，还给出了具有 Cs/O 吸附层的 InGaAs 光电阴极的表面势垒高度的变化。