Improving positive and negative bias illumination stress stability in parylene passivated IGZO transistors

Asal Kiazadeh, Henrique L. Gomes, Pedro Barquinha, Jorge Martins, Ana Rovisco, Joana V. Pinto, Rodrigo Martins, Elvira Fortunato

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

The impact of a parylene top-coating layer on the illumination and bias stress instabilities of indium-gallium-zinc oxide thin-film transistors (TFTs) is presented and discussed. The parylene coating substantially reduces the threshold voltage shift caused by continuous application of a gate bias and light exposure. The operational stability improves by 75%, and the light induced instability is reduced by 35%. The operational stability is quantified by fitting the threshold voltage shift with a stretched exponential model. Storage time as long as 7 months does not cause any measurable degradation on the electrical performance. It is proposed that parylene plays not only the role of an encapsulation layer but also of a defect passivation on the top semiconductor surface. It is also reported that depletion-mode TFTs are less sensitive to light induced instabilities. This is attributed to a defect neutralization process in the presence of free electrons.

Original languageEnglish
Article number051606
JournalApplied Physics Letters
Volume109
Issue number5
DOIs
Publication statusPublished - 1 Aug 2016

Keywords

  • THIN-FILM TRANSISTORS
  • LAYER

Fingerprint Dive into the research topics of 'Improving positive and negative bias illumination stress stability in parylene passivated IGZO transistors'. Together they form a unique fingerprint.

  • Cite this