ROOM-TEMPERATURE CRYSTALLIZATION OF ELECTRONIC OXIDE LAYERS

HEATING ACCOUNTS FOR AROUND 70% OF THE ENERGY CONSUMED IN THE MANUFACTURING PROCESS OF A PRODUCT. THREE QUARTERS OF THIS ENERGY IS STILL SUPPLIED BY FOSSIL FUELS, WHOSE USE IS BEING TAXED BY MOST NATIONAL GOVERNMENTS DUE TO CO2 EMISSIONS. EUROPEAN INDUSTRY HAS MADE TREMENDOUS EFFORTS TO REDUCE ITS ENERGY CONSUMPTION SINCE 2000. THE REASON IS CLEAR: ENERGY IS AN IMPORTANT COST TODAY. ELECTRONICS IS NOT AN EXCEPCION. THE THERMAL OXIDATIVE PROCESS TO PRODUCE VERY THIN LAYERS OF THE ACTIVE ELECTRONIC COMPONENT (E.G. A METAL OXIDE) IS USUALLY CARRIED OUT AT ELEVATED TEMPERATURES. THE INTEGRATION OF METAL OXIDES THEREFORE REQUIRES THE USE OF LARGE AMOUNTS OF HEATING, AS CRYSTALLIZATION NORMALLY TAKES PLACE IN THE RANGE OF 500-800ºC. IF FULL CRYSTALLIZATION IS NOT ACHIEVED, METAL OXIDES SHOW IN GENERAL POOR FUNCTIONALITY, IF ANY. THIS MAKES THE ROOM-TEMPERATURE PROCESSING THE MOST CHALLENGING DEVELOPMENT ENVISIONED FOR THIS FIELD. HOWEVER, THE CRYSTALLIZATION OF OXIDE LAYERS CLOSE TO ROOM TEMPERATURE REQUIRES NOTHING SORT OF A PARADIGM SHIFT IN THE CONVENTIONAL PROCESSING OF THESE MATERIALS BY THERMAL ANNEALING. THE NOVELTY OF THIS PROPOSAL LIES ON THE REVOLUTIONARY CONCEPT OF INDUCING THE ROOM-TEMPERATURE CRYSTALLIZATION OF OXIDE LAYERS BY PHOTOCHEMISTRY, WHERE LIGHT CAN BE USED AS AN ALTERNATIVE ENERGY SOURCE INSTEAD OF CONVENTIONAL HEATING. ITS RADICAL IDEA INVOLVES DIFFERENT STRATEGIES TO REDUCE THE ACTIVATION ENERGY FOR THE OXIDE CRYSTALLIZATION BASED ON MOLECULAR DESIGN, HETEROGENEOUS PHOTOCATALYSIS, ELECTRONIC PHOTOACTIVATION, AND SEEDING NUCLEATION PRINCIPLES. IT IS HYPOTHESIZED THAT A SMART DESIGN OF THE PROCESS CONSIDERING ALL OF THEM WILL PRODUCE A SYNERGISTIC EFFECT THAT PUSHES THE CHEMICAL ENVIRONMENT FAR FROM EQUILIBRIUM, PRODUCING SELECTIVE REACTIONS AND SPECIES THAT ARE NOT ATTAINABLE BY CONVENTIONAL THERMAL PROCESSES. THEN, CRYSTALLIZATION CAN TAKE PLACE BY AN ALTERNATIVE ENERGY SOURCE (LIGHT) AT ROOM TEMPERATURE WITH NULL HEATING ENERGY EXPENDITURE.