Fabrication and electrical and photosensitive properties of silicon nanowire p–n homojunctions

Graded silicon nanowire (SiNW) p–n homojunctions were prepared by an electroless metal deposition method on as‐prepared planar Si p–n junctions made by the B + diffusion method. The nanowire p–n junctions show good rectifying behavior and their turn‐on voltages (0.78 V at room temperature) are found to be independent of the nanowire length. Temperature‐dependent current–voltage properties in the range of 223–363 K were investigated and we demonstrated that the turn‐on voltage decreases from 0.87 V to 0.60 V and the ideality factor n reduces from 8.5 to 3.5 with increasing operating temperature. The results comply very well with the existing p–n junction electron transport mechanism. The potential barrier of a typical SiNW p–n junction obtained through capacitance–voltage measurement accords with its turn‐on voltage. Through I – V and C – V measurements, the nanowire homojunction shows good sensitivity toward visible light and a responsivity of 1.39 A/W under a 5 V reverse bias was obtained. These results present potential applications in future nano‐electronic and photonic devices based on SiNW p–n homojunction arrays. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)