Measures are provided for performing direct radio-frequency to digital conversion. A back electrode is formed on the second main surface so as to be in contact with both of the p-type collector region and the n-type cathode region, and has a titanium layer, a nickel layer and a gold layer that are successively stacked from the side of the second main surface. The chilled air is then used to chill water in either a mixing chamber, or a desalination system, wherein the chilled water is stored in a separation tank, wherein it can later be used to provide cooling for an air conditioning system for a facility. Each of the cut-raised portions corresponds to a respective heat exchanger tube and includes first and second opposed side ends connected to the main body of the fin. The query is used as a frame of reference for the search. , to facilitate interconnectivity among such devices.