Abstract : A review is presented summarizing the specific nuclear microanalysis methods applied in our laboratory to study amorphous semiconductor thin films. For backscattering, ~3 MeV Li ions are applicable when depth resolution and sensitivity are required while up to 8 MeV a-particles allow larger depths to be probed and elemental interferences to be solved. These features are predominant for diffusion studies between metal electrodes and chalcogenide films. On the other hand hydrogen profiling using the 1H(15N, αγ) resonant nuclear reactions is described and analytical problems associated with its use are discussed. Applications to the elaboration conditions of hydrogenated (a)Si is developed.