“…The earlier developed procedure based on neural networks [ 10 , 11 , 29 , 30 , 31 ] for processing of experimentally recorded photoacoustic signals of silicon samples by the open photoacoustic cell [ 32 , 33 , 34 , 35 ] shows effective recognition and removal of instrumental influence [ 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ], and, consequently, provides a detailed and precise characterization of the sample [ 41 , 42 , 43 , 44 , 45 , 46 ]. On the other hand, a very thin TiO 2 layer (nano-layer) is easily deposited in a silicon substrate.…”