True Strain Estimation of Nanomembranes for Energy Band Gap Modification in Electronic and Photonic Devices

Silicon continues to be a leading semiconductor material in the microelectronics industry, offering significant potential for advancing electronic and optoelectronic technologies. However, its indirect energy band gap (1.1 eV) poses a fundamental limitation to achieving high efficiency in next-generation devices. Strain engineering has emerged as a promising technique for modifying the energy band gap, enabling silicon’s application in advanced electronic and photonic devices. In this work, we present a viable method to apply varied tensile strain to a silicon nanomembrane (Si NM) only by eliminating the substrate’s effect and investigate the resulting strain variations using in situ Raman spectroscopy. Moreover, deformation potential theory is used to calculate the variation of the energy band lineup of tensilely strained Si NM. Our findings reveal a substantial significant energy band reduction of approximately 0.24 eV at 0.9% tensile strain. The roughness of the Si NM remains unaltered after we transfer it to a polyimide substrate, with a hole, to achieve a variable and controllable amount of tensile strain. However, the reported method is easily adaptable and can be extended to other NMs bonded to any flexible substrate. These results underscore the potential of tensilely strained Si NMs as versatile and controlled platforms for band structure engineering, offering a precise and efficient approach for enhancing the performance of next-generation devices.