Gopichand Nandamuri

Graphene films were grown on nickel films and foils using chemical vapor deposition. To date, similar growth has been reported at around 1000 degrees C using methane or ethylene as source gases. However, by using acetylene, we have achieved growth of graphene films between 650 and 700 degrees C. The electrical and optical properties, including high resolution transmission electron microscopy of these films, suggest that this technique is both viable and scalable for potential large area optoelectronic applications.

Single and multiple layers of graphene films were grown on (111) oriented single crystals of nickel and polycrystalline nickel films using remote plasma assisted chemical vapor deposition. Remote plasma was employed to eliminate the effect of the plasma electrical field on the orientation of the grown graphene films, as well as to reduce the growth temperature compared to conventional chemical vapor deposition. The electrical and optical properties, including high resolution transmission electron microscopy of these films, suggest that this approach is both versatile and scalable for potential large area optoelectronic applications.

Interdigitated electrode (IDE) arrays with nanometer-scale gaps have been utilized to enhance the sensitivity of affinity-based detection. The geometry of nanogap IDEs was first optimized on the basis of simulations of the electric field and current density. It was determined that the gap (G) between the electrodes was the most important geometric parameter in determining the distribution and strength of the electric field and the current density compared to the width (W) and height (H) of the IDEs. Several devices were materialized and analyzed for their sensitivity to the electrochemical environment using faradic electrochemical impedance spectroscopy (EIS) as the detection technique. Nanogap optimized IDEs were then employed as biosensors for the label-free, affinity-based detection of antitissue transglutaminase antibodies (αtTG-Abs), a biomarker for the detection of autoimmune disorder celiac sprue, triggered by ingesting gluten. The label-free biosensor assay was found to be less sensitive compared to on-chip ELISA. Gold nanoparticles (GNPs) were then employed to improve the sensitivity of the nanogap IDE-based biosensor. With GNPs, the transducer sensitivity increased by 350% over that of label-free detection. The suitability of nanogap IDEs as biosensor transducers for EIS in label-free and GNP-labeled formats was established. The immunobiosensor assay detection sensitivity with the GNPs was found comparable to ELISA.

Arrays of covalently immobilized and aligned graphene ribbons have been successfully prepared on silicon wafers. The effect of covalent modification on the electrical properties of the single-layer graphene was investigated. The effective electron field mobility of the constructed FETs, measured at 2700 cm2V(-1) s(-1), was higher than that for graphene film directly deposited on SiO2, possibly due to lower phonon scattering from the substrate surface, implying that the field effect mobilities may be enhanced with proper choice of substrates. The contact resistance between Cr electrodes and the single-layer graphene ribbon was determined to be 1.62 komega from the TLM structures.

For many organizations, knowledge transfer whether in a co-location setting or virtual setting is one of the most important and challenging aspects of overall knowledge management infrastructure. The purpose of this research report is to explore the challenges faced by ad hoc virtual teams for achieving effective knowledge transfer between the members. In the year 2020, due to a pandemic caused by COVID-19, many industries were forced to follow physical distancing guidelines for the health and safety of their employees. This required many co-location teams to become ad hoc virtual teams. As success of a new member(s) in a team can heavily depend on how well the knowledge was transferred during the on boarding period, research focus for this report further narrowed down to highlight the challenges organizations face to achieve effective knowledge transfer for new members in ad hoc virtual team settings. Literature review has been done and survey questions were developed based on learnings from literature review. Survey questions were formed to collect information from managers & team members on knowledge transfer challenges in virtual environments. 71 survey responses were received, and data was analyzed. Based on this analysis, few practices were proposed to potentially address some of the major challenges reported in the survey.