ECR-Ion Beam Deposition for III-Nitride Semiconductors

WE PROPOSE TO DEVELOP AND STUDY A NEW MANUFACTURING TECHNOLOGY FOR THE EPITAXIAL GROWTH OF MULTILAYERS OF III-NITRIDES SEMICONDUCTORS (GaN AND AlGaN) AT TEMPERATURES SUBSTANTIALLY LOWER THAN PRESENTLY ACHIEVED. THE TECHNIQUE IS BASED ON THE ION BEAM DEPOSITION SYSTEM WHERE THE IONS ARE GENERATED BY AN ELECTRON CYCLOTRON RESONANCE (ECR) MICROWAVE PLASMA. THE ENERGY OF THE IONS INCIDENT ON THE SUBSTRATE ARE CONTROLLED BY A GRID ELECTRODE WHICH ALLOWS THEM TO HAVE THE HIGH SURFACE MOBILITY REQUIRED FOR EPITAXIAL GROWTH AT LOW SUBSTRATE TEMPERATURES. SINCE ECR PLASMAS ARE A RICH SOURCE OF IONIC SPECIES, HIGH DEPOSITION RATE SHOULD BE ACHIEVED USING THIS TECHNIQUE. THE LOW SUBSTRATE TEMPERATURES WILL RESULT IN ABRUPT INTERFACES BETWEEN DIFFERENT LAYERS BECAUSE INTERDIFFUSION BETWEEN LAYERS WILL BE GREATLY REDUCED. FURTHERMORE, LOW SUBSTRATE TEMPERATURES ALSO REDUCE THE STRESS DUE TO DIFFERENT THERMAL EXPANSION COEFFICIENTS OF THE SUBSTRATE AND THE GROWING LAYER. THE USE OF LOW-PRESSURE REACTANTS TO SYNTHESIZE MULTILAYER STRUCTURES WILL GREATLY REDUCE THE MATERIAL COST, WHILE THE AUTOMATION OF THE DEPOSITION PROCESS WILL REDUCE LABOR COSTS. AN ECR PLASMA-ASSISTED METALORGANIC CHEMICAL VAPOR DEPOSITION (PA MOCVD) IS AVAILABLE THAT, WITH MINOR MODIFICATIONS, CAN DEMONSTRATE THIS TECHNOLOGY.