Laplace deep level transient spectroscopy study of intrinsic hydrogenated amorphous silicon

Laplace deep level transient spectroscopy (LDLTS) measurements have been performed on undoped hydrogenated amorphous silicon samples. The LDLTS spectra of annealed and illuminated samples measured at wide range of temperatures show four fully resolved peaks labeled P1, P2, P3, and P4. For annealed samples, only the emission rate corresponding to P1 (the low emission rate one) increases slowly with temperature while all other emission rates are independent of temperature. These peaks were attributed to relaxation process associated with thermal transitions between different charge states of dangling bonds. Contrary to the annealed samples in the fully illuminated samples, all the emission rates corresponding to the LDLTS peaks are independent of temperature but follow, approximately, the same relaxation behavior. It was found that all these defects relaxation follow a power-law dependence of the emission times with the filling pulse duration. Our results don't show any new supplement peaks caused by light soaking of the samples. The light soaking effect was restricted to some changes in the relaxation process and can be readily explained by Adler mechanism.