HIGH-GAIN AVALANCHE PHOTODIODE ARRAYS FOR LONG-WAVELENGTH APPLICATIONS

WE PROPOSE TO DEVELOP HIGH-PERFORMANCE ARRAYS OF INDIUM GALLIUM ARSENIDE (INGAAS) AVALANCHE PHOTODIODES (APDS) FOR FIBER OPTIC, REMOTE SENSING AND SPECTROSCOPY APPLICATIONS INTHE 1.0-1.7 MICRON SPECTRAL BAND. THIS DEVELOPMENT WILL INCREASE ARRAY SENSITIVITY A FACTOR TEN OVER CONVENTIONAL PIN DETECTORS. NO ARRAYS OF THIS TYPE ARE NOW AVAILABLE COMMERCIALLY. THE INNOVATION CONSISTS OF A NOVEL APPLICATION OF A DOPING/THICKNESS PROFILING TECHNIQUE TOGETHER WITH MODIFICATIONS OF THE VAPOR PHASE EPITAXY (VPE)CRYSTAL GROWTH SYSTEM TO PROVIDE UNPRECEDENTED UNIFORMITY INTHICKNESS AND DOPING - TWO PARAMETERS WHICH DRASTICALLY AFFECT APD PERFORMANCE. THE APD STRUCTURE EMPLOYED WILL OPERATE AT ROOM TEMPERATURE AND IS A VERY SIMPLE, PLANAR FLOATING GUARD RING STRUCTURE RECENTLY DEMONSTRATED BY EPITAXX. IT IS THE SIMPLICITY AND TOLERANCE OF THIS LONG-WAVELENGTH DEVICE THAT MAKES IT POSSIBLE FOR US TO CONSIDER FABRICATING ARRAYS OF SUCH STRUCTURES. IN PHASE I,WE WILL GROW INP/INGAAS LAYERS, MEASURE THEIR DOPING-THICKNESS PROFILES (NON-DESTRUCTIVELY), FABRICATE 60 UM DIAMETER APD DEVICES AND CORRELATE THE PROFILES WITH THE YIELD. PROF. S.R. FORREST (USC) WILL CONSULT ON MATERIAL AND DEVICE CHARACTERIZATION. PROF. W.F. KOSONOCKY (NJIT) WILL CONSULT ON ARRAY DESIGN AND READOUT TECHNIQUES. THE YIELD OF CONTIGUOUS APDS WILL BE DETERMINED AND RECOMMENDATIONS FOR IMPROVED UNIFORMITY OF VPE GROWTH WILL BE MADE. THE PHASE II EFFORT WOULD INCLUDE DEVELOPMENT OF A10 ELEMENT LINEAR APD ARRAY INCLUDING READOUT SCHEMES AND CONTROL CIRCUITS. DELIVERABLE PHASE II GOALS INCLUDE A GAINOF 10 AND NEP BELOW 10(-13) W/HZ AT ROOM TEMPERATURE.