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Quinary indium gallium zinc aluminum oxide multicomponent films and thin-film transistors. Ching-Ting Lee 1,2 and Hsin -Ying Lee 3 1 Department of Electrical Engineering, Yuan Ze University, Taoyuan, Taiwan, ROC
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Quinary indium gallium zinc aluminum oxide multicomponent films and thin-film transistors Ching-Ting Lee1,2 and Hsin-Ying Lee3 1Department of Electrical Engineering, Yuan Ze University, Taoyuan, Taiwan,ROC 2Institute of Microelectronics, Department of Electrical Engineering, National Cheng Kung University, Tainan, Taiwan, ROC 3Department of Photonics, National Cheng Kung University, Tainan, Taiwan, ROC
Outline • Introduction • Development of TFT-LCDs • Vapor cooling condensation system • Improve the properties of ZnO-based TFTs • High mobility – optimize atomic ratio of quaternary IGZO TFTs • High stability performance – quinary IGZAO TFTs • Summary
Deposition method of metal oxide films • Sputter [1] • Atomic layer deposition [2] • Aqueous chemical solutions [3] • Chemical vapor deposition [4] • Thermal deposition [5] • Pulsed-laser deposition [6] • Metal-organic chemical deposition [7] • Molecular beam evaporator [8] • Vapor Cooling Condensation System [9] REF: • Thin Solid Films, 150, 283 (1987). • J. Appl. Phys., 103, 033515 (2008). • Nanoscale Res. Lett., 5, 669 (2010). • Cryst. Growth Des., 10, 2011 (2010). • J. Appl. Phys., 106, 064303 (2009). • Chem. Phys. Lett., 479, 125 (2009). • Appl. Phys. Lett., 91, 231901 (2007). • Appl. Phys. Lett., 86, 032909 (2005). • Appl. Phys. Lett., 91, 231113 (2007).
Vapor cooling condensation system Liquid nitrogen • Vacuum system: Material vapor gases were driven directly and thereafter deposited on the substrate. • Liquid nitrogen cooling system: The sublimated materials were condensed rapidly. Sample holder Dopants ZnO RP Multi heat controller Tungsten boat To eliminate defect-related emission from the native defects DP [1] Appl. Phys. Lett., 91, 231113 (2007) [2] J. Appl. Phys. 108, 073119 (2010)
Properties of intrinsic ZnO film Electron concentration and mobility vs. T As grown ZnO Vapor cooling grown ZnO • Similar electron mobility • Vapor cooling grown ZnO smaller electron concentration Lower defect concentration in the vapor cooling grown ZnO
Photoluminescence (PL) spectra • Defect emission intensity of the vapor cooling grown ZnO films is much less. • lower concentration of the point-defects • Total integrating emission intensity of the vapor cooling grown ZnO films is slightly lower. • smaller grain size • higher surface state density • more intense non-radiative relaxation. As grown ZnO Vapor cooling grown ZnO • presence of free-exciton emission at low temperatures • higher ratio of UV emission to visible (defect) emission
LiNO3 co-doping conditions in ZnO LiNO3 deposited with tungsten boat temperature of 495 oC, ZnO deposited with tungsten boat temperature of 1000 oC.
P-type ZnO thin film transistors p-ZnO ZnO+LiNO Appl. Phys. Express 7, 076502, 2014
P-type ZnO thin film transistors Photoelectrochemical passivation
Vapor cooling condensation system Liquid Nitrogen • Vacuum system: Material vapor gases were driven directly and thereafter deposited on the substrate. • Liquid nitrogen cooling system: The sublimated materials were condensed rapidly. Sample holder Rotation Pump Al IGZO Multi Heat Controller Tungsten boat To eliminate defect-related emission from the native defects Diffusion Pump Appl. Phys. Lett., 91(23), 231113 (2007). J. Appl. Phys., 108(7), 073119 (2010).
High quality IGZO films deposition • High temperature deposition make the defect emission obviously. • Low temperature deposition reduce the generation of oxygen vacancy. No defect emission
Quinary IGZAO TFTs • Various Al content affect the electric characteristics of TFTs. • The optimal atomic ratio of Al content was 1.53% for TFTs performances.
Quinary IGZAO TFTs • The IGZAO TFTs had the stable performances as the various temperature. • The turn-on voltage (VON) of the IGZO TFTs and the IGZAO TFTs was 0.6 V and 0.4 V, respectively. ∆VON=0.6 V ∆VON=0.4 V
Quinary IGZAO TFTs • The threshold voltage (Vth) change of the IGZO TFTs and the IGZAO TFTs was 0.5 V and 0.3 V as temperature from 225 K to 300 K. • The subthreshold swing change of the IGZO TFTs and the IGZAO TFTs was 0.05 V/decade and 0.03 V/decade as temperature from 225 K to 300 K. IGZAO TFTs (with Al content of 1.53%) ∆Ns: Maximum density state change ∆Ns of IGZO TFTs= 8.651010 eV-1cm-2 ∆Ns of IGZAO TFTs= 5.191010 eV-1cm-2 ∆S: subthreshold swing change, k: Boltzmann constant, T: absolute temperature, COX: capacitance per unit area
Extra transport pathway Co-sputter with Al target and IGZO target (In:Ga:Zn:O = 1.3:0.4:1:3.3) The added Al3+ ions were interstitially located between 5 s orbitals of In3+ ions. J. Appl. Phys., 117(4), 045309 (2015).
Stability of Indium Gallium Zinc Aluminum Oxide Thin-Film Transistors with Treatment Processes Schematics configuration of the IGZAO TFTs
Stability of Indium Gallium Zinc Aluminum Oxide Thin-Film Transistors with Treatment Processes (a) (b) Drain-source current drain-source voltage transfer characteristics of (a) the IGZO TFTs and (b) the IGZAO TFTs after O2 plasma treatment and post-annealing treatment.
Stability of Indium Gallium Zinc Aluminum Oxide Thin-Film Transistors with Treatment Processes V Hysteresis comparisons of the IGZO TFTs and the IGZAO TFTs with the O2 plasma and post-annealing treatments.
Stability of Indium Gallium Zinc Aluminum Oxide Thin-Film Transistors with Treatment Processes (a) (b) PBTS behavior of (a) the IGZO TFTs and (b) the IGZAO TFTs with the O2 plasma and post-annealing treatments under various stress times.
Stability of Indium Gallium Zinc Aluminum Oxide Thin-Film Transistors with Treatment Processes (a) (b) Hot carrier effect of (a) the IGZO TFTs and (b) the IGZAO TFTs with various stress times, measured at DS= 2 V
High stability performance of quinary indium gallium zinc aluminum oxide films and thin-film transistors deposited using vapor cooling condensation method Schematic diagram of the bottom gate type IGZAO TFTs.
High stability performance of quinary indium gallium zinc aluminum oxide films and thin-film transistors deposited using vapor cooling condensation method Photoluminescence characteristics of IGZO films and IGZAO films deposited with and without liquid nitrogen cooling. The enlargement of the curve shown in the inset.
High stability performance of quinary indium gallium zinc aluminum oxide films and thin-film transistors deposited using vapor cooling condensation method Electron concentration and electron mobility of LT-IGZO films and LT-IGZAO films with an Al 1.53 at% was measured at the temperature from 225 K to 300 K.
High stability performance of quinary indium gallium zinc aluminum oxide films and thin-film transistors deposited using vapor cooling condensation method Drain-source current drain-source voltage characteristics of IGZO TFTs and IGZAO TFTs with an Al 1.53 at%.
High stability performance of quinary indium gallium zinc aluminum oxide films and thin-film transistors deposited using vapor cooling condensation method Drain-source current gate-source voltage transfer characteristics of the IGZO TFTs and the IGZAO TFTs with an Al 1.53 at%.
High stability performance of quinary indium gallium zinc aluminum oxide films and thin-film transistors deposited using vapor cooling condensation method Transfer characteristics dependent on temperature of (a) IGZO TFTs and (b) IGZAO TFTs with an Al 1.53 at%.
High stability performance of quinary indium gallium zinc aluminum oxide films and thin-film transistors deposited using vapor cooling condensation method Threshold voltage change and subthreshold swing value change of IGZO TFTs and IGZAO TFTs as a function of temperature.
Quinary IGZAO TFTs NanoclusterScattering Al ions interstitialAl3+ replace Zn2+ OFR=O2/(Ar+O2) At 45 W obtain higher mobility Extra transport pathway Co-sputter with Al target and IGZO target (In:Ga:Zn:O = 1.3:0.4:1:3.3) The added Al3+ ions were interstitially located between 5 s orbitals of In3+ ions. Better stability for aging times [10] J. Appl. Phys., 117(4), 045309 (2015).
Quinary IGZAO TFTs Al-O bonds: 1.Helpful to maintain the quality of O ions 2.Avoid to generate a large number of new oxygen vacancies High performances & Stability V=0.6V Vth = X-1/2 VDSVth= 2.1 V IGZO IGZAO V=0.2V Vth= 1.9 V
Quinary IGZAO TFTs Al-O bonds: 1.Helpful to maintain the quality of O ions 2.Avoid to generate new oxygen vacancies V=0.2V IGZO IGZAO More Stable V~0V