ELECTRICALLY REVERSIBLE DEPASSIVATION PASSIVATION MECHANISM IN POLYCRYSTALLINE SILICON/

An electrically reversible depassivation/passivation phenomenon has be en found for hydrogen passivated polysilicon. This reversible effect i s seen in both ECR and rf hydrogen passivated n-channel thin films tra nsistors (TFTs) but is not seen in the corresponding hydrogen passivat ed p-channel TFTs, nor is it seen in either n- or p-channel TFTs befor e hydrogenation. This phenomenon was observed while room temperature b ias stressing n- and p-channel TFTs fabricated on the same solid phase crystallized polysilicon films on quartz substrates. A model involvin g hydrogen release or capture at defects and positively charged hydrog en motion in device electric field is proposed. This phenomenon has si gnificant implications for polysilicon TFT design and operation. (C) 1 996 American Institute of Physics.