NOVELTY - The method involves converting energy from electromagnetic waves in a silicon on insulator substrate (32) into heat. The energy from the heat is converted into electricity using vertical super-grids (30), and electrical charges are stored. The light is concentrated for being focalized on a structured zone of the substrate using a micro lens (31), where the micro lens is made of glass or transparent polymer resin.    USE - Method for converting electromagnetic waves into electricity in a thermoelectric/thermoionic generator (claimed). Uses include to micro-electronic device and communication nodes in an autonomous wireless sensor network, transport system e.g. vehicle or aircraft, infrastructure e.g. automation and securing infrastructure of dwelling or industrial maintenance infrastructure, and environment e.g. pollution monitoring environment or environment for analyzing atmosphere of a deployment zone.    ADVANTAGE - The method converts the electromagnetic waves into electricity with high power density in a simple, inexpensive, efficient and reliable manner. The vertical super-grid is manufactured with quasi-infinite number of layers using less number of technological stages. The method generates power based on possibilities of machining of silicon at sub-micrometric and nanometric scales and deposition qualities. The lens ensures simple and efficient protection of an active part of an energy converter from external medium, thus improving reliability of the converter.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a thermoelectric/thermoionic generator for implementing an electromagnetic wave converting method    (2) a method for fabricating a vertical super-grid.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of super-grids suspended on silicon on insulator substrate.    Super-grids (30)    Micro lens (31)    Silicon on insulator substrate (32)    Hot point (33)    Incident electromagnetic radiation (36)    Air or vacuum compartment (37)