FINITE ELEMENT THERMODYNAMIC MODEL OF MULTI-ZONE CDTE VERTICAL BRIDGMAN GROWTH LEADING TO IMPROVED YIELDS OF ELECTROOPTIC MODULATOR

CDTE ELECTROOPTC MODULATOR CYSTALS UP TO10X10X50MM3 WILL BE THE DEVICE OF CHOICE IN MANY CO2 LASER RADAR SYSTEMS UNDER DEVELOPMENT BY AFAL. THE OBJECTIVES OF THIS WORK IS TO SIGNIFICANTLY RAISE CURRENTLY LOW YIELDS IN THE MANUFACTURE OF LARGE ELECTROOOPTIC GRADE CDTE SINGLE CRYSTALS THEREBY IMPROVING THE PRODUCIBLITY OF CDTE MODULATORS. PHASE I WILL INCLUDE: 1. A LITERATURE SEARCH OF OPTIMUMCONDITIONS FOR CRYSTAL GROWTH GENRALLY AND FOR CDTE SPECIFICALLY. 2. ASSESSMENT OF THE VERTICAL BRIDGMAN (VB) METHOD AS THE MOST PROMISING TECHNOLOGY FOR DEVELOPMENT. 3. DEVELOPMENT OF A COMPUTERIZED FINITE ELEMENT THERMODYNAMIC MODEL OF THE VB PROCESS. 4. CORRELATION OF PREDICTED WITH ACTUAL VB GROWTH FURNANCE PERFORMANCE DATA TO ESTABLISH MODELING FEASIBILITY. 5. USE OF THE MODEL TO ANALYZE VB CONFIGRUATIONS AND VARIATIONS AND TO DEVELOP RECOMMENDATIONS AS TO WHICH CONFIGURATIONS PRODUCE FAVORABLE GROWTH CONDITIONS. PHASE II (NOT PART OF THIS PROPOSAL) IS ENVISIONED TO INCLUDE: 1. REFINEMENT OF MOST PROMISING VB CONFIGURATIONS. 2. VB GROWTH UTILIZING THESE CONFIGURATIONS. 3. ENHANCEMENT OF THE MODEL TO IMPROVE RESOLUTION AND SENSITIVITY. 4. DEVELOPMENT OF ACCURATE YIELD DATA AS GROWTH CONFIGURATION IMPROVE.