Effect of Si nanoparticles on electronic transport mechanisms in P-doped silicon-rich silicon nitride/c-Si heterojunction devices

We successfully fabricated hetero-junction (H-J) devices from P-doped silicon-rich SiN_x embedded with Si nanoparticles on a p-type crystalline Si substrate at low temperature. High-resolution transmission electron microscopy (HRTEM) analysis indicates that the thin films contain nano-crystallites. The H-J devices showed a good rectification ratio at room temperature. Three distinct regions of temperature dependent J-V characteristics curve can be identified, where different current density variations are indicated. In the low voltage range, the current across the interface of H-J follows an ohmic behavior. In the intermediate range of voltage, the current transport mechanism shows a transition from the phosphorus diffusion to tunneling dominant due to the silicon nanoparticle size and interface of HJ device changed, while the space-charge-limited current (SCLC) dominates the conduction mechanism in the high voltage range and the density of trapping states also affects the electron transport proceeding. At last, the proper size of silicon nanoparticle can reduces the interface charge density of H-J, which is confirmed via the numerical C-V matching technique and we propose a new energy band diagram to fit the HJ device embedded by the silicon nanoparticles.