Investigation of Donor and Acceptor Ion Implantation in AlN

AlN is an attractive material for power electronics device applications due to its wide bandgap and resulting high electric breakdown field. One of the major challenges that need to be addressed to achieve full utilization of AlN for power electronics applications is the development of a doping strategy for both donors and acceptors. Ion implantation is a particularly attractive approach since it allows for selected-area doping of semiconductors due to its high spatial and dose control and its high throughput capability. Active layers in the semiconductor are created by implanting a dopant species followed by very high temperature annealing to reduce defects and thereby activate the dopants. Application of Multicycle Rapid Thermal Annealing (MRTA) has demonstrated excellent results for annealing high dose implanted GaN. This approach has excellent potential for application with AlN. An effection annealing technique is one of the key capbabilities currently lacking from AlN ion implantation technology. The application and thorough study of this process for AlN implanted materials is anticipated to provide a means for creating n- and p-type AlN with high impurity concentrations and with excellent recovery from implantation induced radiation damage. In Phase I AlN layers will be grown by metalorganic chemical vapor deposition and implanted with chemical species such as Si and Mg. Rigorous annealing studies will be performed and the resulting free carrier concentrations determined as a function of the annealing schedules. The result of Phase I will be demonstration of a semi-optimized annealing schedule for AlN implanted material. Additionally a thorough characterization of hole hopping conduction in acceptor degenerate AlN which occurs at high impurity concentrations. Phase II will focus on the application of these techniques for fabrication of high power electronic devices. Commercial Applications and Other Benefits: AlGaN alloys with high Al composition and AlN based electronic devices are attractive for high voltage, high temperature applications, including microwave power sources, power switches and communication systems. These wide bandgap devices have large potential markets for enhancing efficiency of power conversion in nearly all areas. Estimated market potential for wide bandgap devices is well into the billion $ range within the next several years. The ability to control conductivity of AlN will unlock the materials extraordinary properties for various high power device designs.