Transport Properties of Nanostructures

The current-voltage (I-V) properties of an InP nanowire and a CdS nanosheet are studied. Back to back metal semiconductor metal contacts are modeled based on thermionic emission theory and field emission theory. These are used to explain the I-V characteristics of these nanostructures which enables measurement of the important intrinsic properties including donor density and electrical conductivity of nanostructures. Photolithography followed by lift-off is used to fabricate the Al/Ti contact pads across these nanostructures for transport measurements. Scanning photocurrent microscopy (SPCM) is used to see the variation of photocurrent along the nanostructure. The SPCM image shows that the peak photocurrent always appears at the reverse biased metal-semiconductor contact edge indicating strong localization of electric field which is also confirmed by numerical simulation.