Project Grant 2520250

COLLABORATIVE RESEARCH: ASCENT: WAFER-SCALE SUB-THZ REFLECTARRAY FOR ELECTRICAL NEEDLE BEAM FORMING AND STEERING -IN THIS ASCENT PROJECT, THE TEAM AIMS TO DEVELOP A SET OF SEMICONDUCTOR TECHNOLOGIES, INCLUDING NEW DEVICE FABRICATION, LARGE-SCALE HETEROGENEOUS INTEGRATION, AND ROBUST BEAM-ALIGNMENT SYSTEM ARCHITECTURES, TO ACHIEVE ELECTRICALLY CONTROLLED COLLIMATION OF ELECTROMAGNETIC WAVES IN SUB-TERAHERTZ (SUB-THZ) FREQUENCY BANDS AT LOW COST. COMPARED TO THE EXISTING 5G WIRELESS BANDS BELOW 100 GHZ, THE SUB-THZ BANDS OFFER UNPRECEDENTED WIDE BANDWIDTH THAT CAN ENABLE ULTRA-FAST DATA RATE FOR DATA CENTER NETWORKING AND WIRELESS INFRASTRUCTURE, AS WELL AS HIGH PRECISION FOR RADAR AND IMAGING. THE ELECTRONIC HARDWARE DEVELOPED IN THIS PROJECT PROVIDES A HIGHLY DESIRABLE FUNCTION FOR MOST SUB-THZ SYSTEMS -- FOCUSING THE BEAM POWER WITHIN ONE DEGREE IN SPACE (HENCE THE TERM NEEDLE BEAM IN THE PROJECT TITLE) WITH HIGH-PRECISION ELECTRONIC CONTROL OF THE BEAM DIRECTION. THE NEW HARDWARE ARCHITECTURE ENABLES WIRELESS COMMUNICATION SYSTEMS TO ACHIEVE A HIGH DATA RATE UP TO 120 GBPS OVER A DISTANCE GREATER THAN ONE KILOMETER. IT ALSO ENABLES RADAR IMAGING SYSTEMS TO ACHIEVE HIGH-RESOLUTION SENSING OF THE AMBIENT ENVIRONMENT, WHICH IS CRITICAL FOR ALL-WEATHER SAFE OPERATION OF AUTONOMOUS VEHICLES. IN ADDITION, THIS PROJECT NOT ONLY PROVIDES EXTENSIVE GRADUATE RESEARCHER TRAINING IN HIGH-FREQUENCY CIRCUIT DESIGNS AND ADVANCED SEMICONDUCTOR MANUFACTURING BUT ALSO PROMOTES STEM EDUCATION THROUGH VARIOUS PROGRAMS. NEEDLE BEAM FORMING AT 140 GHZ REQUIRES LARGE (> 70X70 MILLIMETER SQUARE) ELECTRONIC PHASE-CONTROLLING SURFACES WITH LOW SIGNAL LOSS AT HIGH FREQUENCIES. THEREFORE, TRANSISTORS FABRICATED USING ADVANCED LITHOGRAPHY ARE NEEDED. RECENT DEMONSTRATIONS OF SUB-THZ REFLECTARRAY USING EITHER TILED COMPLEMENTARY METAL-OXIDE-SEMICONDUCTOR (CMOS) FINFET CHIPS OR CHIP PACKAGE MODULES HAVE EXCESSIVELY HIGH FABRICATION AND ASSEMBLY COSTS. IN THIS PROJECT, THE TEAM EXPLORES A NEW DIRECT WAFER-SCALE INTEGRATION APPROACH THROUGH LOW-TEMPERATURE FABRICATIONS OF CUSTOM METAL-INSULATOR-SEMICONDUCTOR-INSULATOR-METAL (MISIM) VARIABLE CAPACITANCE DEVICES AND HIGH-EFFICIENCY SUB-THZ ANTENNAS ON TOP OF A FOUNDRY-PROCESSED INTEGRATED-CIRCUIT GLASS SUBSTRATE. WITHOUT USING ANY EXPENSIVE ADVANCED LITHOGRAPHY, THE DEVICES CAN STILL ACHIEVE LOW-LOSS PHASE SHIFTING OF SUB-THZ SIGNALS, HENCE SIGNIFICANTLY REDUCING THE COST OF THE NEEDLE-BEAM-FORMING SYSTEM. THE PROJECT ALSO INVESTIGATES NEW REFLECTARRAY CIRCUITS THAT PERFORM SELF-CORRECTION OF DEVICE DEFECTS AND PROCESS VARIATIONS, AS WELL AS NEW REFLECTARRAY TRANSCEIVER ARCHITECTURES THAT ENABLE COMPACT OVERALL SYSTEM FORM FACTOR AND HIGH-PRECISION BEAM ALIGNMENT. THIS AWARD REFLECTS NSF'S STATUTORY MISSION AND HAS BEEN DEEMED WORTHY OF SUPPORT THROUGH EVALUATION USING THE FOUNDATION'S INTELLECTUAL MERIT AND BROADER IMPACTS REVIEW CRITERIA.- SUBAWARDS ARE NOT PLANNED FOR THIS AWARD.