Wang Gaoxue, Zhang Jinlin, Huang Chengkun, Dimitrov Dimitre A, Alexander Anna, Simakov Evgenya I
Theoretical Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM, 87545, USA.
Accelerator Operations and Technology Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM, 87545, USA.
Sci Rep. 2025 Jan 22;15(1):2780. doi: 10.1038/s41598-024-85054-z.
The pursuit to operate photocathodes at high accelerating gradients to increase brightness of electron beams is gaining interests within the accelerator community, particularly for applications such as free electron lasers (FEL) and compact accelerators. Cesium telluride (CsTe) is a widely used photocathode material and it is presumed to offer resilience to higher gradients because of its wider band gap compared to other semiconductors. Despite its advantages, crucial material properties of CsTe remain largely unknown both in theory and experiments. In this study, we employ first-principles calculations to provide detailed structural, elastic, electronic and transport properties of CsTe. It is found that CsTe has an intrinsic mobility of 20 cm/Vs for electrons and 2.0 cm/Vs for holes at room temperature. The low mobility is primarily limited by the strong polar optical phonon scattering. CsTe also exhibits ultralow lattice thermal conductivity of 0.2 W/(m*K) at room temperature. Based on the energy gain/loss balance under external field and electron-phonon scattering, we predict that CsTe has a dielectric breakdown field in the range from ~ 60 to ~ 132 MV/m at room temperature dependent on the doping level of CsTe. Our results are crucial to advance the understanding of applicability of CsTe photocathodes for high-gradient operation.
在加速器领域，人们对在高加速梯度下运行光阴极以提高电子束亮度的追求越来越感兴趣，特别是在自由电子激光（FEL）和紧凑型加速器等应用中。碲化铯（CsTe）是一种广泛使用的光阴极材料，由于其与其他半导体相比具有更宽的带隙，被认为能够承受更高的梯度。尽管CsTe有诸多优点，但其关键材料特性在理论和实验方面仍大多未知。在本研究中，我们采用第一性原理计算来提供CsTe详细的结构、弹性、电子和输运特性。研究发现，在室温下，CsTe中电子的本征迁移率为20 cm²/V·s，空穴的本征迁移率为2.0 cm²/V·s。低迁移率主要受强极性光学声子散射的限制。CsTe在室温下还表现出超低的晶格热导率，为0.2 W/(m·K)。基于外场下的能量得失平衡和电子 - 声子散射，我们预测在室温下，根据CsTe的掺杂水平，其介电击穿场在约60至约132 MV/m范围内。我们的结果对于推进对CsTe光阴极用于高梯度运行适用性的理解至关重要。
