Noise Aspects of some Si-based One Port Devices and Carbon Nanotubes

The p-n junctions and Schottky diodes based on Si_1-xGe_x and SiC are of great importance in modern electronic applications, such as microwave detectors and mixers. Carbon nanotubes (CNTs) have appeared recently as an attractive new class of materials with a reduced dimensionality, and proposed as building blocks for nanoelectronic technology. <p />In this thesis, we have investigated the noise properties of 6H-SiC p-n junctions, some metal/Si_1-xGe_x Schottky contacts, and multiwall carbon nanotubes (MWNTs). Since the noise in electronic devices is very sensitive to any processing variation, and sets a lower limit to the quantities to be measured, it is important to know the factors contributing to these limits and use this knowledge to optimize operating conditions. <p />Concerning the impact of device size on the noise behavior, we have studied the low frequency noise in 6H-SiC ion implanted diodes with three different active areas. Two relationships between the noise spectral density and the active area have been found to describe the noise behavior observed in these devices. Regarding Schottky contacts, we have characterized the effect of the annealing, plasma etching, high-energy irradiation, co-sputtering and thermal reaction on the noise performance of these junctions. From the experimental data at different temperatures, we have found noise sources, physical parameters and optimum operating conditions. Furthermore, we have used the noise measurement as a diagnostic tool to detect defects, interface states and extraction of their activation energy levels, and hence evaluated the performance of technology. In the last part of this thesis, we have given interest to the newly observed material, CNTs. The excess noise in one individual and two crossing MWNTs was measured, characterized, and compared to that observed in many other conductors and semiconductor devices