2D materials have been interesting for applications into nanodevices due to their intriguing physical properties. In this work, four types of unique structures are designed that are composed of MXenes and C/N-Si layers (CNSi), where MXene is sandwiched by the CNSi layers with different thicknesses, for their practical applications into integrated devices. The systematic calculations on their elastic constants, phonon dispersions, and thermodynamic properties show that these structures are stable, depending on the composition of MXene. It is found: 1) different from MXene or N-functionalized MXene (M2CN2), SiN2/M2X/SiN2 possess new electronic properties with free carriers only in the middle, leading to 2D free electron gas; 2) CNSi/MXene/CNSi shows an intrinsic Ohmic semiconductor-metal-semiconductor (S-M-S) contact, which is potential for applications into nanodevices; and 3) O/M2C/SiN2 and N/M2C/OSiN are also stable and show different electronic properties, which can be semiconductor or metal as a whole depending on the interface. A method is further proposed to fabricate the 2D structures based on the industrial availability. The findings may provide a novel strategy to design and fabricate the 2D structures for their application into nanodevices and integrated circuits.