Effect of the ambient field on the I–V characteristics of nanowire resistors and junctions—A simulation study

Ambient field refers to the field lines outside the semiconductor that are caused by the potential difference between points on the semiconductor. We present a TCAD study of the effects of the ambient field on the I–V characteristics of NanoWire (NW) resistors and junctions. The study covers different contact geometries, hi–lo as well as p–n junctions, and practical bias range including the equilibrium condition; effects of varying the wire radius, length, doping and ambient dielectric constant are brought out. The NWs studied have radii≥15 nm and length≥500 nm for which classical models based on drift–diffusion transport are applicable. Simple qualitative explanations for various non-linear shapes of the I–V characteristics are provided using field lines. An appealing analogy is presented for the rise in the carrier concentration of an undoped NW grown on a heavily doped substrate. The study is aimed at improving the understanding of nanoscale devices and proper interpretation of their experimental data.

We present a TCAD study of the effects of the ambient field on the I–V characteristics of NanoWire resistors, hi–lo junctions and p–n junctions, considering different contact geometries.Figure optionsDownload as PowerPoint slideHighlights
► The ambient field modifies the shape of the I–V characteristics of nanowires (NWs).
► This field causes a ‘capillarity’ like rise of carriers in a NW on a conducting substrate.
► Extension of the contact at one end of the wire increases the above effects.
► The above effects are stronger for NWs with lower values of diameter and doping.
► The effects are elucidated using simulated field lines and potential distributions.