TY - JOUR
T1 - Hydrogen Behavior at Crystalline/Amorphous Interface of Transparent Oxide Semiconductor and Its Effects on Carrier Transport and Crystallization
AU - Medvedeva, Julia E.
AU - Sharma, Kapil
AU - Bhattarai, Bishal
AU - Bertoni, Mariana I.
N1 - Funding Information:
The authors acknowledge support from the National Science Foundation (NSF) DMREF program (grants DMR-1729779 and DMR-1842467) and from the Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy (EERE), SETO FY20 program (grant DE-EE0009346). The computational resources were provided by Missouri S&T and by the NSF-MRI program (grant OAC-1919789).
Publisher Copyright:
© 2022 American Chemical Society.
PY - 2022/8/31
Y1 - 2022/8/31
N2 - 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.
AB - 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.
KW - ab initio molecular dynamics
KW - carrier generation and transport
KW - crystalline/amorphous interfaces
KW - crystallization
KW - density functional theory
KW - hydrogen defects
KW - wide-band-gap amorphous oxide semiconductors
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U2 - 10.1021/acsami.2c09604
DO - 10.1021/acsami.2c09604
M3 - Article
C2 - 35984223
AN - SCOPUS:85137135940
SN - 1944-8244
VL - 14
SP - 39535
EP - 39547
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 34
ER -