Dielectric properties of BaMg1∕3Nb2∕3O3 doped Ba0.45Sr0.55Tio3 thin films for tunable microwave applications
Ba(Mg1∕3Nb2∕3)O3 (BMN) doped and undoped Ba0.45Sr0.55TiO3 (BST) thin films were deposited via radio frequency magnetron sputtering on Pt/TiO2/SiO2/Al2O3 substrates. The surface morphology and chemical state analyses of the films have shown that the BMN doped BST film has a smoother surface with redu...
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
World Scientific Publishing
2015-12-01
|
| Series: | Journal of Advanced Dielectrics |
| Subjects: | |
| Online Access: | http://www.worldscientific.com/doi/pdf/10.1142/S2010135X15500307 |
| _version_ | 1818954041250545664 |
|---|---|
| author | Fikadu Alema Konstantin Pokhodnya |
| author_facet | Fikadu Alema Konstantin Pokhodnya |
| author_sort | Fikadu Alema |
| collection | DOAJ |
| description | Ba(Mg1∕3Nb2∕3)O3 (BMN) doped and undoped Ba0.45Sr0.55TiO3 (BST) thin films were deposited via radio frequency magnetron sputtering on Pt/TiO2/SiO2/Al2O3 substrates. The surface morphology and chemical state analyses of the films have shown that the BMN doped BST film has a smoother surface with reduced oxygen vacancy, resulting in an improved insulating properties of the BST film. Dielectric tunability, loss, and leakage current (LC) of the undoped and BMN doped BST thin films were studied. The BMN dopant has remarkably reduced the dielectric loss (∼38%) with no significant effect on the tunability of the BST film, leading to an increase in figure of merit (FOM). This is attributed to the opposing behavior of large Mg2+ whose detrimental effect on tunability is partially compensated by small Nb5+ as the two substitute Ti4+ in the BST. The coupling between MgTi″ and VO•• charged defects suppresses the dielectric loss in the film by cutting electrons from hopping between Ti ions. The LC of the films was investigated in the temperature range of 300–450K. A reduced LC measured for the BMN doped BST film was correlated to the formation of defect dipoles from MgTi″, VO•• and NbTi• charged defects. The carrier transport properties of the films were analyzed in light of Schottky thermionic emission (SE) and Poole–Frenkel (PF) emission mechanisms. The result indicated that while the carrier transport mechanism in the undoped film is interface limited (SE), the conduction in the BMN doped film was dominated by bulk processes (PF). The change of the conduction mechanism from SE to PF as a result of BMN doping is attributed to the presence of uncoupled NbTi• sitting as a positive trap center at the shallow donor level of the BST. |
| first_indexed | 2024-12-20T10:15:51Z |
| format | Article |
| id | doaj.art-575903e84d9545e58918bae6ed088b15 |
| institution | Directory Open Access Journal |
| issn | 2010-135X 2010-1368 |
| language | English |
| last_indexed | 2024-12-20T10:15:51Z |
| publishDate | 2015-12-01 |
| publisher | World Scientific Publishing |
| record_format | Article |
| series | Journal of Advanced Dielectrics |
| spelling | doaj.art-575903e84d9545e58918bae6ed088b152022-12-21T19:44:03ZengWorld Scientific PublishingJournal of Advanced Dielectrics2010-135X2010-13682015-12-01541550030-11550030-910.1142/S2010135X1550030710.1142/S2010135X15500307Dielectric properties of BaMg1∕3Nb2∕3O3 doped Ba0.45Sr0.55Tio3 thin films for tunable microwave applicationsFikadu Alema0Konstantin Pokhodnya1Center for Nanoscale Science and Engineering, North Dakota State University, Fargo, ND 58108, USACenter for Nanoscale Science and Engineering, North Dakota State University, Fargo, ND 58108, USABa(Mg1∕3Nb2∕3)O3 (BMN) doped and undoped Ba0.45Sr0.55TiO3 (BST) thin films were deposited via radio frequency magnetron sputtering on Pt/TiO2/SiO2/Al2O3 substrates. The surface morphology and chemical state analyses of the films have shown that the BMN doped BST film has a smoother surface with reduced oxygen vacancy, resulting in an improved insulating properties of the BST film. Dielectric tunability, loss, and leakage current (LC) of the undoped and BMN doped BST thin films were studied. The BMN dopant has remarkably reduced the dielectric loss (∼38%) with no significant effect on the tunability of the BST film, leading to an increase in figure of merit (FOM). This is attributed to the opposing behavior of large Mg2+ whose detrimental effect on tunability is partially compensated by small Nb5+ as the two substitute Ti4+ in the BST. The coupling between MgTi″ and VO•• charged defects suppresses the dielectric loss in the film by cutting electrons from hopping between Ti ions. The LC of the films was investigated in the temperature range of 300–450K. A reduced LC measured for the BMN doped BST film was correlated to the formation of defect dipoles from MgTi″, VO•• and NbTi• charged defects. The carrier transport properties of the films were analyzed in light of Schottky thermionic emission (SE) and Poole–Frenkel (PF) emission mechanisms. The result indicated that while the carrier transport mechanism in the undoped film is interface limited (SE), the conduction in the BMN doped film was dominated by bulk processes (PF). The change of the conduction mechanism from SE to PF as a result of BMN doping is attributed to the presence of uncoupled NbTi• sitting as a positive trap center at the shallow donor level of the BST.http://www.worldscientific.com/doi/pdf/10.1142/S2010135X15500307Barium strontium titanatesputteringferroelectric thin filmtunabilityleakage currentpermittivitylossfigure of meritdefect dipole |
| spellingShingle | Fikadu Alema Konstantin Pokhodnya Dielectric properties of BaMg1∕3Nb2∕3O3 doped Ba0.45Sr0.55Tio3 thin films for tunable microwave applications Journal of Advanced Dielectrics Barium strontium titanate sputtering ferroelectric thin film tunability leakage current permittivity loss figure of merit defect dipole |
| title | Dielectric properties of BaMg1∕3Nb2∕3O3 doped Ba0.45Sr0.55Tio3 thin films for tunable microwave applications |
| title_full | Dielectric properties of BaMg1∕3Nb2∕3O3 doped Ba0.45Sr0.55Tio3 thin films for tunable microwave applications |
| title_fullStr | Dielectric properties of BaMg1∕3Nb2∕3O3 doped Ba0.45Sr0.55Tio3 thin films for tunable microwave applications |
| title_full_unstemmed | Dielectric properties of BaMg1∕3Nb2∕3O3 doped Ba0.45Sr0.55Tio3 thin films for tunable microwave applications |
| title_short | Dielectric properties of BaMg1∕3Nb2∕3O3 doped Ba0.45Sr0.55Tio3 thin films for tunable microwave applications |
| title_sort | dielectric properties of bamg1 3nb2 3o3 doped ba0 45sr0 55tio3 thin films for tunable microwave applications |
| topic | Barium strontium titanate sputtering ferroelectric thin film tunability leakage current permittivity loss figure of merit defect dipole |
| url | http://www.worldscientific.com/doi/pdf/10.1142/S2010135X15500307 |
| work_keys_str_mv | AT fikadualema dielectricpropertiesofbamg13nb23o3dopedba045sr055tio3thinfilmsfortunablemicrowaveapplications AT konstantinpokhodnya dielectricpropertiesofbamg13nb23o3dopedba045sr055tio3thinfilmsfortunablemicrowaveapplications |