Das Arkaprava, Partyka-Jankowska Ewa, Zając Marcin, Hemberg Axel, Bittencourt Carla
Chimie des Interaction Plasma Surface, University of Mons, Place du Parc 23, 7000 Mons, Belgium.
SOLARIS National Synchrotron Radiation Centre, Jagiellonian University, Czerwone Maki 98, 31-007 Krakow, Poland.
ACS Omega. 2024 Feb 14;9(8):9835-9846. doi: 10.1021/acsomega.4c00892. eCollection 2024 Feb 27.
The impact of different synthesis parameters, such as thickness, postsynthesis annealing temperature, and oxygen gas flow rate, upon the electronic structure is discussed in detail in the present experimental investigation. X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) spectroscopy techniques are used to evaluate the surface electronic properties along with the presence and stability of the CdO surface oxide in CdZnO ( = 0.4) composite thin films. The thin films were synthesized with varying thicknesses using a CdZnO (CZO) ceramic and CdZn (CZ) metallic targets and oxygen gas flow rates during magnetron sputtering. The Zn L edge and O K edge XANES spectra are affected by the oxygen gas flow rate. For the zero rate, an increase in intensity is observed in the Zn L edge, and notable changes occur in the overall spectral features of the O K edge. In the films synthesized in the presence of oxygen, highly probable O 2p → antibonding Zn 3d electronic transitions decrease the probability of the Zn 2p → antibonding Zn 3d electronic transition by filling the vacant antibonding Zn 3d states, leading to the reduction in overall intensity in the Zn L edge. Scanning electron microscopy reveals grain growth with increasing annealing temperature. The annealing induces orbital hybridization, generating new electronic states with higher transition probabilities and intensity enhancement in both Zn L and O K edges. The presence of the CdO surface phase is confirmed by analyzing the Cd 3d and O 1s XPS core levels. The CdO surface phase is observed in the films synthesized using the CZO target for all thicknesses, while the CZ target is only observed for higher thicknesses. Further postsynthesis annealing treatment results in the disappearance of the CdO phase. The CdO surface phase can be controlled by varying the film thickness and postsynthesis annealing temperature.
在本实验研究中，详细讨论了不同合成参数，如厚度、合成后退火温度和氧气流量，对电子结构的影响。采用X射线光电子能谱（XPS）和X射线吸收近边结构（XANES）光谱技术来评估CdZnO（= 0.4）复合薄膜中CdO表面氧化物的存在情况及其稳定性，以及表面电子性质。在磁控溅射过程中，使用CdZnO（CZO）陶瓷靶、CdZn（CZ）金属靶以及不同的氧气流量，合成了不同厚度的薄膜。氧气流量会影响Zn L边和O K边的XANES光谱。对于零流量情况，Zn L边的强度增加，并且O K边的整体光谱特征发生显著变化。在有氧气存在的情况下合成的薄膜中，高度可能的O 2p→反键Zn 3d电子跃迁通过填充空的反键Zn 3d态，降低了Zn 2p→反键Zn 3d电子跃迁的概率，导致Zn L边的整体强度降低。扫描电子显微镜显示，随着退火温度的升高晶粒生长。退火诱导轨道杂化，产生具有更高跃迁概率的新电子态，并增强了Zn L边和O K边的强度。通过分析Cd 3d和O 1s的XPS核心能级，证实了CdO表面相的存在。对于所有厚度的使用CZO靶合成的薄膜都观察到了CdO表面相，而仅在较高厚度的使用CZ靶合成的薄膜中观察到了CdO表面相。进一步的合成后退火处理导致CdO相消失。CdO表面相可以通过改变薄膜厚度和合成后退火温度来控制。
