Superlattices electrical transport

In this chapter we review the work done in our laboratory on the structure (Part II), optical absorption (Part III), photoluminescence (Part IV), and electrical transport (Part V) of a-Si H/a-SiNjci H superlattices. Results with single quantum well structures are discussed by Kukimoto in Chapter 12 of Volume 2ID. 

Beverly et al. [93] studied the temperature-dependent DC transport measurements on monolayers of self-assembled dodecanethiol-coated 7 nm silver nanoparticles as a function of particle size distribution-induced disorder. The superlattices disorder was adjusted by a stepwise variation of the particle size distribution. In the electrical transport measurements, six different monolayers of 7 nm silver nanoparticles, in which the size distribution was varied from 6.6% to 13.8%, were investigated at 300-10 K. Above 200 K, all films exhibited metallic conductivity, and below 200 K activated transport. However, between 30 and 100 K a second transition (Tcross) was observed that was based on the crossover from the simply activated transport to a... 

Superlattice structures yield efficient charge transport normal to the layers, because the charge carriers can move through the minibands the narrower the barrier, the wider the miniband and the higher the carrier mobility. Transport in MQWs with thick barriers requires thermionic emission of carriers over the barriers, or if electric fields are applied, field-assisted tunnelling through the barriers (Parsons et al, 1990). 

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