Large Piezoelectriclike Response from Inhomogeneously Deformed Silicon Crystals
Dongxia Tian, Yu Hou, Qi Pan, Baojin Chu
Abstract
Silicon ($\mathrm{Si}$) crystals are important materials for the modern microelectronics industry. While $\mathrm{Si}$ crystals are not piezoelectric materials due to their centrosymmetric structure, it is found in this work that $\mathrm{Si}$ crystals exhibit a large piezoelectric-like response under bending deformation. We show that this response is not intrinsic, but rather originates from the surfaces of crystals that are slightly oxidized upon their exposure to air. The weak piezoelectric response of the surface is amplified by high conductivity of the bulk and bending deformation of $\mathrm{Si}$ plates. In addition, the piezoelectric-like response is strongly dependent on the conduction type and the resistivity of the crystals and on the metal electrode used for piezoelectric measurements. A multilayer model is proposed to explain the piezoelectric-like response of the $\mathrm{Si}$ crystals. This finding may be exploited to design piezoelectric devices using $\mathrm{Si}$ only, without the integration of additional piezoelectric materials, and is important for understanding the $\mathrm{Si}$ crystal surfaces.