Create: Materials growth experts in the ESTD employ a wide range of methods to realize advanced elemental and compound semiconductors, high-κ dielectrics, and second-order materials. These include physical techniques, such as molecular beam epitaxy and reactive sputtering, and chemical techniques, such as metalorganic chemical vapor deposition, high temperature chemical vapor deposition, and atomic layer deposition and epitaxy. These capabilities allow design and creation of materials from the atomic scale to the micrometer scale and covering the full range of electronic, magnetic, optical, and thermal properties to bring advanced device concepts within reach.
Assess: The ESTD has an impressive range of expert-operated characterization capabilities. In situ techniques give real-time feedback during electronic material (EM) growth, while post-growth analysis resolves bulk, surface, and interfacial structure/composition with atomic precision. Key methods include transmission electron and scanning tunneling microscopies and x-ray diffraction and topography. Spectroscopic probes are employed to evaluate electronic properties such as band gap and carrier lifetime. Carrier density and mobility are measured with Hall systems, one operating between 2.2 and 325 K with a 0 to 9 tesla magnet. Defects limiting device and material performance are assessed by imaging recombination centers and extended defects and by point defect identification.
Integrate: Realizing the ultimate functionality of advanced EMs involves precise fabrication of electronic devices with a high degree of complexity. ESTD researchers use state-of-the-art processing techniques to selectively add and remove metals, insulators, and semiconductors to and from previously synthesized EMs. Features can be patterned from 30 nanometers (~100 atoms) to hundreds of micrometers (about the diameter of a human hair). EMs can be added by thermal or electron-beam evaporation, sputtering, or other synthesis methods, or EMs can be removed using techniques such as wet chemical, reactive ion, or inductively coupled plasma etching. To join dissimilar materials that cannot be synthesized directly, wafer bonding is employed.