Nanostructure Absorption: A Comparative Study of Nanowire and Colloidal Quantum Dot Absorption Cross Sections

There has recently been much work on using nanowires for various applications. Examples include photodectors and photovoltaics. One of the main reasons for this stems from the nanowires asymmetric shape which in principle, facilitates the ready band transport of carriers. As a consequence, effective mobilities should be larger than those of comparable quantum dot devices. At the same time, a less recognized advantage of nanowires over nanocrystals is their sizable absorption cross sections. Namely, circularly polarized nanowire cross sections in the visible are routinely on the order of 10(-12) cm(2) mu m(-1) to 10(-10) cm(2) mu m(-1) whereas those of dots range from 10(-15) cm(2) to 10(-18) cm(2). When scaled for volume differences, best case nanowire cross sections are still larger than those of nanocrystals by roughly an order of magnitude. This could in turn, offer additional benefits for nanowire-based devices.