Vertically aligned ZnO nanorods grown by a wet chemical method were implanted with O + ions with three different ion fluences: ( Φ ) = 5 × 10 14, 5 × 10 15, and 5 × 10 16 ions/cm 2. It is observed that the concentration of Oxygen vacancies (O V) introduced by implantation first increases from 25.94 % to 54.76 % with increasing Φ and decreases beyond Φ = 5 × 10 15 ions/cm 2. We attribute this to the knocking out of oxygen atoms from the host matrix, which gets saturated due to the presence of an ample amount of O + ions inside the host matrix beyond Φ = 5 × 10 15 ions/cm 2 and further confirmed by extended x-ray absorption fine structure measurements. Therefore, the abundant O V becomes more delocalized followed by overlapping with the maxima of valence bands resulting in the narrowing of the bandgap of ∼ 0.4 eV. The appearance of an additional Raman peak at ∼ 575 cm − 1 in Raman spectra further confirmed the presence of impurity states. It is evident that at a fixed J = 100 μA/cm 2, the turn-on field increases from 3.61 V/ μm to 6.61 V/ μm with increasing Φ, and as a result of this, the field-enhancement factor ( β) decreases. We attribute this increase in turn-on field as a consequence of charge trapping in deep-level states created by O V.

中文翻译：

---

通过 O+ 离子辐照缺陷工程调整 ZnO 纳米棒的场发射特性

用湿化学法生长的垂直排列的 ZnO 纳米棒注入 O + 离子，具有三种不同的离子注量：( Φ ) = 5 × 10 14、5 × 10 15 和 5 × 10 16 离子/cm 2。据观察，由注入引入的氧空位 (OV) 浓度首先随着 Φ 的增加而从 25.94 % 增加到 54.76 %，并在超过 Φ = 5 × 10 15 离子/cm 2 时减少。我们将此归因于从宿主基质中敲除氧原子，由于主体基质中存在超过 Φ = 5 × 10 15 离子/cm 2 的大量 O + 离子而变得饱和，并通过扩展的 X 射线吸收精细结构测量进一步证实。因此，丰富的 OV 变得更加离域，然后与价带的最大值重叠，导致带隙变窄约 0.4 eV。在拉曼光谱中在~575 cm - 1 处出现额外的拉曼峰进一步证实了杂质态的存在。很明显，在固定的 J = 100 μA/cm 2 下，随着 Φ 的增加，开启场从 3.61 V/ μm 增加到 6.61 V/ μm，因此，场增强因子 ( β )减少。我们将这种导通场的增加归因于 O V 产生的深能级状态中的电荷俘获。