HIGH GROWTH RATE ATOMIC LAYER EPITAXY OF GAN AND ALGAN FOR ADVANCED OPTOELECTRONIC DEVICES

RESEARCHERS ARE DEMONSTRATING ATOMIC LAYER EPITAXY (ALE) OF GAN/AIN STRUCTURES AT GROWTH RATES EXCEEDING 1 MICRON/HR IN AN INNOVATIVE REACTOR WHICH EMPLOYS CONTINUOUSLY FLOWING, YET SPATIALLY SEPARATE, GAS STREAMS AND A MOVING SUBSTRATE TO EXPOSE THE WAFER SURFACE TO ALTERNATING FLUXES OF GROUP III AND V REACTANTS. THE REACTOR INCORPORATES BOTH STRUCTURAL AND GAS CURTAIN BARRIERS TO ENSURE FAST AND EFFICIENT REMOVAL OF THE EXCESS REACTANTS AND REACTION PRODUCTS WHICH LIMIT ALE GROWTH RATES. THEIR REMOVAL IS ACHIEVED BY COUPLING MECHANICAL BOUNDARY LAYER SHEARING WITH HYDROGEN PURGING TO PREVENT GAS-PHASE MIXING OF THE TWO REACTANT SPECIES. IN THIS WAY A PROCESS WHICH COMBINES THE SUPERIOR THICKNESS AND COMPOSITIONAL UNIFORMITY OF ALE WITH THE HIGH GROWTH RATE OF METALORGANIC CHEMICAL VAPOR DEPOSITION (MOCVD) CAN BE ACHIEVED. TO SHOW FEASIBILITY, RESEARCHERS ARE USING ALE-GROWN MATERIAL TO FABRICATE A FUNCTIONAL PHOTOCONDUCTIVE UV DETECTOR. ONCE PROPER CONTROL OF DOPANTS IS DEMONSTRATED, HIGH GROWTH RATE ALE WILL BE EXPLORED AS A MEANS OF PRODUCING P-N JUNCTION DEVICES SUCH AS LASERS, LIGHT EMITTING DIODES, AND PHOTODIODES. THE EXCELLENT UNIFORMITY OF MATERIAL GROWN BY ALE WILL ALSO MAKE POSSIBLE THE REALIZATION OF TWO-DIMENSIONAL STARING UV DETECTOR ARRAYS.