Engineering the carrier lifetime and switching speed in Si-based mm-wave photomodulators
Engineering the carrier lifetime and switching speed in Si-based mm-wave photomodulators
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DOI：
10.1063/5.0128234
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发表时间：
2022-12
影响因子：
3.2
通讯作者：
I. Hooper;E. Khorani;X. Romain;L. E. Barr;T. Niewelt;Sandeep Saxena;A. Wratten;N. Grant;J. Mur
中科院分区：
文献类型：
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作者：
I. Hooper;E. Khorani;X. Romain;L. E. Barr;T. Niewelt;Sandeep Saxena;A. Wratten;N. Grant;J. Mur
对于各种各样的半导体器件，电荷载流子寿命是一个重要的特性。然而，载流子寿命难以控制，因为它通常由各种复合过程决定。对于间接带隙材料，众所周知，有效载流子寿命可以通过钝化表面来提高，有效地消除表面相关的复合过程。然而，对于某些应用，例如用于亚红外辐射的光调制器，将寿命定制为特定值是有益的，在这种特定情况下，在光效率和切换速度之间进行权衡。本文设计了一种新型的电子空穴寿命可调的硅基超材料。通过周期性地图案化介电表面钝化层，我们创建了超材料，由此钝化区域相对于未钝化区域的填充分数决定了有效电荷载流子寿命。我们在670 μm厚的Si晶片上展示了200 μs和8 ms之间的可调寿命，尽管原则上我们的方法允许在体半导体的完全钝化和未钝化极限之间产生任何寿命。最后，我们研究了这些超材料作为光调制器的应用，发现开关时间取决于光激发强度、晶片厚度和载流子寿命。
For a diverse range of semiconductor devices, the charge carrier lifetime is an essential characteristic. However, the carrier lifetime is difficult to control, as it is usually determined by a variety of recombination processes. For indirect bandgap materials, it is well known that effective carrier lifetimes can be improved by passivating the surface, effectively extinguishing surface-related recombination processes. However, for some applications, such as photomodulators for sub-infrared radiation, it is beneficial to tailor lifetimes to specific values, in this particular case trading off between photo-efficiency and switching speed. In this paper, we design a new type of silicon-based metamaterial with a tunable electron–hole lifetime. By periodically patterning a dielectric surface passivation layer, we create a metamaterial whereby the filling fraction of passivated relative to unpassivated areas dictates the effective charge carrier lifetime. We demonstrate tunable lifetimes between 200 μs and 8 ms in a 670 μm thick Si wafer, though in principle our approach allows one to generate any lifetime between the fully passivated and unpassivated limits of a bulk semiconductor. Finally, we investigate the application of these metamaterials as photomodulators, finding switching times that depend upon both the photoexcitation intensity, wafer thickness, and the carrier lifetime.