Bulk devices

The introduction of a new architecture such as nanomaterials necessitates the need for new terminology and methods of classification and characterization. We must also understand the mechanisms by which individual nanostructures may assemble into larger materials, as this will greatly affect the properties of the bulk device for a particular application. This chapter will focus on all of these important issues, with an introduction to the various types of nanomaterials, laboratory techniques used for their synthesis, and (perhaps most importantly) their role in current/future applications. 

The most commonly used crystals in BAW devices are 5, 9, or 10 MHz quartz in the form of 10-16 mm disks that are approximately 0.15 mm thick. Metals are often evaporated directly onto the quartz plates to serve as electrodes. The metal electrodes are 3000-10000 A thick and 3-8 mm in diameter and can be made of gold, silver, aluminum, or nickel (figure 19.2). SAW devices, however, are capable of operating at much higher frequencies than the bulk devices and normally crystals of more than 100 MHz resonant frequency are used. Therefore,... 

Ideally Iq = OA at all bias conditions. Imperfect gate dielectrics, surface conduction, bulk device transport, or a lack of semiconductor patterning can lead to gate leakage and affect the performance of many circuits. 

High-Tc- superconductors Dielectrics Thin film/bulk devices capacitors, sensors, phase shifters, dynamic RAMS YB32C U307, BsTi03... 

Whereas CM in bulk materials is usually determined in photocurrent device measurements, that is, by collecting the carriers, CM in QDs is studied by (optical) spectroscopic measurements, in which the orbital occupation of the QDs is probed on ultrafast (picosecond) timescales. Hence, the commonly used experimental procedures to determine CM in QDs (ultrafast spectroscopy) and in bulk (device measurements) are rather different. While time-resolved optical and IR spectroscopies are ideally suited to probe carrier populations in colloidal QDs, " light of terahertz (THz) frequencies interacts strongly with free carriers in the bulk material and allows the direct characterization of carrier density and mobility. From THz-time domain spectroscopy (TDS) experiments, one can quantitatively assess the number of photogenerated carriers in bulk semiconductors picoseconds after the light is absorbed. Additionally, as a result of the contact-free nature of the THz probe, it is possible to determine the CM factor in isolated samples of bulk semiconductors without the need to apply contacts, which is necessary in the device measurements. For these reasons, THz-TDS experiments have been employed to quantify CM in bulk PbSe and PbS on ultrafast timescales " in order to make a bulk-QD comparison in the context of the CM controversy. The CM factor in bulk PbS and PbSe was determined for excitation with various photon energies from the UV to the IR. 

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