Measuring the Electronic Properties of Materials at the Nanoscale

Abstract

The general objective of electronic property measurements is to relate extrinsic characteristics of devices or test structures to the intrinsic properties of materials. When there are significant nanoscale inhomogeneities in macroscale materials, or the materials themselves are nanoscale, the measurement of electronic properties at high spatial resolution may be essential to the fundamental understanding of structure–property relationships. This chapter is intended to serve as a framework for the consideration of measuring the electronic properties of materials at the nanoscale, and as a guide to the use of other articles in this volume. Background is provided on general principles of nanoscale measurement, approaches to nanofabrication that enable investigation of nanoscale and nanostructured materials, and distinct regimes of transport that inform the interpretation of electrical measurements. Specific techniques that exploit local probe–sample interactions are introduced according to their principles of operation, to either locally measure characteristics of a material or to generate a local perturbation material that is detected remotely. This framework is used to organize the chapter in terms operational mechanisms of techniques, rather than outcomes of measurement. Noncontact measurements that generate knowledge of local electronic properties are also examined. The chapter is not strictly limited to techniques that provide nanoscale resolution, but rather techniques that resolve electronic properties on length scales over which said properties may vary. The chapter focuses on generally accessible measurements of practical importance to understanding and optimizing the properties of materials with readily envisioned applications.

Biosynthesis and Chemical Applications of Thioamides

“…61,62 Like YcfC in 6TG biosynthesis, IscS is a PLP-dependent cysteine desulfurase which transfers the sulfur atom of cysteine to generate a persulfide (R-SSH) group on an active site cysteine residue. 63 The terminal sulfur of the persulfide is then transferred to ThiI (s 4 U synthetase) where it also resides on an active site cysteine in what is referred to as a rhodanese homology domain (RHD, Cys456 in E. coli ThiI). 64,65 The N-terminal portion of ThiI, which is composed of three domains (ferredoxin-like, THUMP, and pyrophosphatase), is responsible for tRNAbinding and activating uridine-8 using ATP while the C-terminal portion delivers sulfur to the adenylated uridine in tRNA.…”

Barrier Height Measurement of Metal Contacts to Si Nanowires Using Internal Photoemission of Hot Carriers

“…The Schottky barrier height is often extracted by analyzing current–voltage ( I–V ) or capacitance–voltage ( C–V ) characteristics based on the thermionic emission model, which due to its simplicity has been widely adopted for measuring the barrier height in nanostructured devices incorporating semiconductor nanowires. − However, electrical biasing changes the population of surface states, which complicates the interpretation of the measurement. Furthermore, the geometry of nanowire contacts differs from that used in strictly one-dimensional models of transport in Schottky diodes, impacting the extracted barrier height and ideality factor. , In general, determining a reliable barrier height in small, highly doped nanowires is nontrivial but critical to the optimization of highly scaled electronic, optoelectronic, spintronic, and chemical-biological sensor devices …”

“…Furthermore, the geometry of nanowire contacts differs from that used in strictly one-dimensional models of transport in Schottky diodes, impacting the extracted barrier height and ideality factor. 9,10 In general, determining a reliable barrier height in small, highly doped nanowires is nontrivial 8 but critical to the optimization of highly scaled electronic, optoelectronic, spintronic, and chemical-biological sensor devices. 1 Recently, there has been increasing interest in exploiting hot carrier transport across interfacial barriers for applications including photovoltaics, 11 photodetectors, 4 and light-emitting devices.…”