Control of the shielding and the transmission of an electro-magnetic wave (∼GHz) by a visible light using flexible CdS films grown on polymer substrates

Relationship between the dark- (without a light) and photo- (with a light) resistance values by a visible light is addressed using non-stoichiometric CdS:H films grown on polyethersulfon (PES) flexible polymer substrates at room temperature by radio frequency magnetron sputtering technique. The CdS:H films deposited at a hydrogen flow ratio of 25% exhibited a dark- and photo-sheet resistance of 2.7 × 105 and ∼50 Ω/square, respectively. These values were realized by an optimum control of both hydrogen doping-levels and the surface morphologies of the films. The comparison between the real and the simulated results for the shielding and the transmission by the free space measurement system in the X-band frequency range (8.2–12.4 GHz) was also addressed in this study. Samples overlapped with 13 layers of CdS:H films were consistent with the transmission results of pure aluminum metal films (0.1 Ω/square) deposited on PES substrates. By the simple stacking of the CdS:H layers, the perfect control of the shielding and the transmission of the EM wave in the range of X-band frequency is possible by a visible light alone.