| Space based electronic systems such as communications satellites and interplanetary space probes have become increasingly important since their inception in the mid 20th century. However, as these systems become smaller and more sophisticated, the ability to carry radiation shielding to protect against the space radiation environment becomes more difficult. Therefore, new lightweight, radiation resilient electronics are needed to meet the demands of new probe designs. Current silicon based transistors rely on charged separated regions prone to radiation, which can disrupt normal operation. Novel nanomaterials that may be inherently radiation resilient offer promising alternatives. Recent research suggests that nanomaterials and nanomaterial based electronic devices may have inherent radiation resiliency due to their reduced dimensionalities, and in some eases enhanced self-healing due to their nanoscale sizes.; Low to high-Z heavy ion irradiation experiments, including heavy ion beams of krypton-86, krypton-78 and calcium-48, were conducted to explore fundamental heavy ion nanomaterial interactions. Nanomaterials irradiated included carbon nanotubes, gallium nitride nanowires and carbon onions. Real time gallium nitride nanowire-based circuit operation in radiation was also investigated using special vault. Results were highly encouraging and promise high payoff, given their high radiation resilience and superior materials and electronic performance.; Newly discovered gallium nitride (GaN) nanowires used in radiation investigations were unique multiphase nanowires that incorporated zinc-blende and wurtzite crystalline domains that grew in the longitudinal direction simultaneously. Structural properties of the multiphase nanowires were studied using high-resolution transmission electron microscopy. Plain-view high-resolution transmission electron microscopy (HRTEM) was used to identify the presence of both the zinc-hlende and wurtzite crystalline phases present in the nanowire. Cross-section HRTEM was used to identify the domain orientation relationships within the nanowire. Scanning electron microscopy (SEM) investigations identified growth temperature dependence on GaN matrix features that led to the multiphase nanowire growth. HRTEM investigations of the sides of GaN hexagonal platelets, from which nanowires grew, revealed a network of nanoscale ledges. These ledges were identified as the nanowire nucleation sites.; Electronic properties of individual nanowires using nanomanipulator probes, cathodoluminescence, and nanowires integrated into devices were investigated. Using four-point probe techniques the intrinsic nanowire resistance was accurately measured. Using two-point probe techniques, evidence of single-phase transport was observed, where a large liquid protrusion emerged from the nanowire, while an outer structure remained in tact. Cathodoluminescence showed possible electron confinement effects and stress in the multiphase nanowire system. Gallium nitride nanowire-based field effect transistors were also fabricated and studied. All measurements indicated that the nanowires were capable of high current densities. |
