Ultrabroadband density of states of amorphous In-Ga-Zn-O
The subgap density of states of amorphous indium gallium zinc oxide (a-IGZO) is obtained using the ultrabroadband photoconduction response of thin-film transistors (TFTs). Density-functional theory simulations classify the origin of the measured subgap density of states peaks as a series of donorlik...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
American Physical Society
2020-09-01
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| Series: | Physical Review Research |
| Online Access: | http://doi.org/10.1103/PhysRevResearch.2.033358 |
| _version_ | 1797211297513734144 |
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| author | Kyle T. Vogt Christopher E. Malmberg Jacob C. Buchanan George W. Mattson G. Mirek Brandt Dylan B. Fast Paul H.-Y. Cheong John F. Wager Matt W. Graham |
| author_facet | Kyle T. Vogt Christopher E. Malmberg Jacob C. Buchanan George W. Mattson G. Mirek Brandt Dylan B. Fast Paul H.-Y. Cheong John F. Wager Matt W. Graham |
| author_sort | Kyle T. Vogt |
| collection | DOAJ |
| description | The subgap density of states of amorphous indium gallium zinc oxide (a-IGZO) is obtained using the ultrabroadband photoconduction response of thin-film transistors (TFTs). Density-functional theory simulations classify the origin of the measured subgap density of states peaks as a series of donorlike oxygen vacancy states and acceptorlike Zn vacancy states. Donor peaks are found both near the conduction band and deep in the subgap, with peak densities of 10^{17}−10^{18}cm^{−3}eV^{−1}. Two deep acceptorlike peaks lie adjacent to the valance-band Urbach tail region at 2.0–2.5 eV below the conduction-band edge, with peak densities in the range of 10^{18}cm^{−3}eV^{−1}. By applying detailed charge balance, we show that increasing the deep acceptor density strongly shifts the a-IGZO TFT threshold voltage to more positive values. Photoionization (hν>2.0eV) of deep acceptors is one cause of transfer curve hysteresis in a-IGZO TFTs, owing to longer recombination lifetimes as electrons are captured into acceptorlike vacancies. |
| first_indexed | 2024-04-24T10:24:15Z |
| format | Article |
| id | doaj.art-d5e5868446bb459d932299954c102e52 |
| institution | Directory Open Access Journal |
| issn | 2643-1564 |
| language | English |
| last_indexed | 2024-04-24T10:24:15Z |
| publishDate | 2020-09-01 |
| publisher | American Physical Society |
| record_format | Article |
| series | Physical Review Research |
| spelling | doaj.art-d5e5868446bb459d932299954c102e522024-04-12T17:00:01ZengAmerican Physical SocietyPhysical Review Research2643-15642020-09-012303335810.1103/PhysRevResearch.2.033358Ultrabroadband density of states of amorphous In-Ga-Zn-OKyle T. VogtChristopher E. MalmbergJacob C. BuchananGeorge W. MattsonG. Mirek BrandtDylan B. FastPaul H.-Y. CheongJohn F. WagerMatt W. GrahamThe subgap density of states of amorphous indium gallium zinc oxide (a-IGZO) is obtained using the ultrabroadband photoconduction response of thin-film transistors (TFTs). Density-functional theory simulations classify the origin of the measured subgap density of states peaks as a series of donorlike oxygen vacancy states and acceptorlike Zn vacancy states. Donor peaks are found both near the conduction band and deep in the subgap, with peak densities of 10^{17}−10^{18}cm^{−3}eV^{−1}. Two deep acceptorlike peaks lie adjacent to the valance-band Urbach tail region at 2.0–2.5 eV below the conduction-band edge, with peak densities in the range of 10^{18}cm^{−3}eV^{−1}. By applying detailed charge balance, we show that increasing the deep acceptor density strongly shifts the a-IGZO TFT threshold voltage to more positive values. Photoionization (hν>2.0eV) of deep acceptors is one cause of transfer curve hysteresis in a-IGZO TFTs, owing to longer recombination lifetimes as electrons are captured into acceptorlike vacancies.http://doi.org/10.1103/PhysRevResearch.2.033358 |
| spellingShingle | Kyle T. Vogt Christopher E. Malmberg Jacob C. Buchanan George W. Mattson G. Mirek Brandt Dylan B. Fast Paul H.-Y. Cheong John F. Wager Matt W. Graham Ultrabroadband density of states of amorphous In-Ga-Zn-O Physical Review Research |
| title | Ultrabroadband density of states of amorphous In-Ga-Zn-O |
| title_full | Ultrabroadband density of states of amorphous In-Ga-Zn-O |
| title_fullStr | Ultrabroadband density of states of amorphous In-Ga-Zn-O |
| title_full_unstemmed | Ultrabroadband density of states of amorphous In-Ga-Zn-O |
| title_short | Ultrabroadband density of states of amorphous In-Ga-Zn-O |
| title_sort | ultrabroadband density of states of amorphous in ga zn o |
| url | http://doi.org/10.1103/PhysRevResearch.2.033358 |
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