Improvement in the determination by 1/f noise measurements of the interface state distribution in polysilicon TFTs in relation with the compensation law of Meyer Neldel

Laurent Pichon (1) , Abdelmalek Boukhenoufa (2) , Bogdan Cretu (2) , Regis Rogel (1)

1 IETR - Institut d'Électronique et des Technologies du numéRique
2 Equipe Electronique - Laboratoire GREYC - UMR6072

Low-frequency (1/f ) noise is studied in N-channel furnace solid phase crystallized (FSPC) and in laser solid phase crystallized (LSPC) polysilicon TFTs biased from weak to strong inversion. Noise analysis is supported by the theory of charge carrier trapping/detrapping at the interface tunnelling into gate oxide traps. The distribution of interface trap states (NT) is deduced from the number of carriers trapped into the oxide. Noise measurements for devices biased from weak to moderate inversion allow the determination of the distribution of deep level trap states associated with dangling bonds type defects (NTdb); whereas measurements from moderate to strong inversion give the distribution of shallow level trap states (NTts) associated with strained bonds defects. The noise analysis clearly shows that the slope of both exponential distributions equals to the reverse of the Meyer Neldel energy EMN (0.035 eV and 0.055eV for FSPC and LSPC TFT respectively). For LSPC devices the resulting distribution of interface states (NT=NTdb+NTts) is one decade lower and it is attributed to the effects of the laser annealing on the active layer crystal quality.

Mots clés: Meyer Neldel law; TFT; 1/ noise; Interface states distribution

Domaines: Micro et nanotechnologies/Microélectronique

Laurent Pichon, Abdelmalek Boukhenoufa, Bogdan Cretu, Regis Rogel. Improvement in the determination by 1/f noise measurements of the interface state distribution in polysilicon TFTs in relation with the compensation law of Meyer Neldel. Journal of Applied Physics, 2009, 105, pp.104503. ⟨10.1063/1.3126706⟩. ⟨hal-00387394⟩