INNOVATIVE GROWTH TECHNIQUE FOR INFRARED DETECTORS: ATOMIC LAYER EPITAXY

WE PROPOSE TO DEVELOP AN ATOMIC LAYER EPITAXY (ALE) TECHNIQUE WHEREBY THE CRYSTAL GROWTH OF SINGLE ATOMIC LAYERS WILL BE APPLIED TO THE FABRICATION OF INFRARED DETECTOR ARRAYS WITH EXTREMELY HIGH UNIFORMITY IN THE 0.5 TO 3 MICRON SPECTRAL RANGE. THE USE OF LAYER GROWTH ELIMINATES THICKNESS AND COMPOSITIONAL VARIATIONS ACROSS A WAFER. THUS NON-UNIFORMITIES DUE TO THERMAL GRADIENTS AND VAPOR DEPLETION ARE ELIMINATED SINCE CRYSTAL GROWTH WOULD DEPEND ON KINETIC FACTORS, RATHER THAN ON THERMODYNAMICS OR MASS TRANSPORT PHENOMENA. DETECTOR ARRAYS PRODUCED WOULD HAVE PERFORMANCE UNIFORMITIES FAR BETTER THAN ANYTHING PRESENTLY AVAILABLE AND MULTI-ELEMENT ARRAYS - POSSIBLY SEVERAL HUNDRED ELEMENTS -COULD BE MADE. OTHER DEVICE STRUCTURES SUCH AS QUANTUM WELLS AND STAIRCASE AVALANCHE PHOTODIODES, WOULD ALSO BE POSSIBLE WITH THIS THIN LAYER TECHNIQUE, PHASE I WOULD CONSIST OF BUILDING AN OPTIMIZED REACTOR SPECIFICALLY DESIGNED FOR ALE AND MAKING HIGH PERFORMANCE DETECTOR ARRAYS. TRANSMISSION ELECTRON MICROSCOPE MEASUREMENTS OF ATOMIC LAYER THICKNESS WILL BE PERFORMED AT THE MATERIALS SCIENCE CENTER OF THE UNIVERSITY OF VIRGINIA.