Investigation of silicon nanowires photodetector

Abstract

Silicon nanowires (SiNWs) research has intensified over the past decade with the advancement in nanowires fabrication technology. The objectives of this study are to (i) develop a fabrication process to obtain top-down SiNWs with cross-sectional dimensions of 10 nm or less, (ii) characterize the physical structures of the SiNWs, (iii) form SiNWs p+-n+ and p+-p-n+ diodes along the nanowires and (iv) characterize the SiNWs diodes under dark and illuminated conditions to gain an understanding of the nanoscale junction devices.

The diodes fabricated consist of multiple SiNWs of 1 μm long connected in parallel, as well as larger dimension bulk diodes that are served as control diodes. Three different batches of diodes were fabricated. Batch 0 samples demonstrated the successful fabrication of SiNWs p+-p-n+ diodes. The subsequent fabrication was to examine the formation of the nanowires and to improve the electrical characteristics of the SiNWs diodes. The silicon fin width and oxidation time were reduced in batch 1 samples fabrication. Silicon oxide was deposited on the SiNWs as passivation, to replace the thermal oxide that was removed for the purpose of inspection. The last round of fabrication was to reduce the high leakage current observed in batch 1 diodes. The batch 2 samples have either deposited or thermal oxides as passivation for the SiNWs. The dopant activation time was reduced from 20 s to 5 s in batch 2 samples.