Hydrogen Behavior at Crystalline/Amorphous Interface of Transparent Oxide Semiconductor and Its Effects on Carrier Transport and Crystallization

Julia E. Medvedeva, Kapil Sharma, Bishal Bhattarai, Mariana I. Bertoni

Research output: Contribution to journalArticlepeer-review

Abstract

The role of disorder and particularly of the interfacial region between crystalline and amorphous phases of indium oxide in the formation of hydrogen defects with covalent (In-OH) or ionic (In-H-In) bonding are investigated using ab initio molecular dynamics and hybrid density-functional approaches. The results reveal that disorder stabilizes In-H-In defects even in the stoichiometric amorphous oxide and also promotes the formation of deep electron traps adjacent to In-OH defects. Furthermore, below-room-temperature fluctuations help switch interfacial In-H-In into In-OH, creating a new deep state in the process. This H-defect transformation limits not only the number of free carriers but also the grain size, as observed experimentally in heavily H-doped sputtered In2Ox. On the other hand, the presence of In-OH helps break O2 defects, abundant in the disordered indium oxide, and thus contributes to faster crystallization rates. The divergent electronic properties of the ionic vs covalent H defects passivation of undercoordinated In atoms vs creation of new deep electron traps, respectively and the different behavior of the two types of H defects during crystallization suggest that the resulting macroscopic properties of H-doped indium oxide are governed by the relative concentrations of the In-H-In and In-OH defects. The microscopic understanding of the H defect formation and properties developed in this work serves as a foundation for future research efforts to find ways to control H species during deposition.

Original languageEnglish (US)
Pages (from-to)39535-39547
Number of pages13
JournalACS Applied Materials and Interfaces
Volume14
Issue number34
DOIs
StatePublished - Aug 31 2022

Keywords

  • ab initio molecular dynamics
  • carrier generation and transport
  • crystalline/amorphous interfaces
  • crystallization
  • density functional theory
  • hydrogen defects
  • wide-band-gap amorphous oxide semiconductors

ASJC Scopus subject areas

  • Materials Science(all)

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