Electrical Activation Studies of Silicon Implanted Aluminum Gallium Nitride with High Aluminum Mole Fraction; Dissertation

摘要

This research demonstrates a method for producing highly conductive Si-implanted n-type aluminum gallium nitride (AlxGa1-xN) alloys, and represents a comprehensive analysis of the resulting material's electrical and optical properties as a function of Al mole fraction, anneal temperature, anneal time, and implantation dose. Highly conductive alloys are critical to the fabrication of devices operating in deep UV, high-temperature, high-power, and high- frequency environments, and thus this research is significant in regard to the application of such devices. The AlxGa1-xN wafers of this study, with Al concentrations of 10 to 50%, were implanted at room temperature with silicon ions at energies of 200 keV with doses of 1x1014, 5x1014, and 1x1015 cm-2 and annealed from 1100 to 1350 C for 20 to 40 minutes in flowing nitrogen. Excellent activation was achieved for each of the implanted silicon doses for all of the five Al mole fractions studied, with most activation efficiencies above 90%. These activation efficiencies are the highest reported activations, to the best of my knowledge. The mobilities were found to decrease as the Al concentration of the AlxGa1-xN was increased from 10 to 50% and also as the implanted silicon dose was increased. Typical mobilities ranged from 101 cm2/V s for the Al0.1Ga0.9N implanted with 1x1014 cm-2 silicon ions to 35 cm2/V s obtained for the Al0.5Ga0.5N implanted with 1x1015 cm-2 silicon ions. The cathodoluminescence results support the electrical results in determining the optimal annealing conditions.