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Electroluminescence, charge trapping and quenching in Eu implantes SiO2–Si structures
Microelectronic Engineering 86 (2009) 1954–1956
Contents lists available at ScienceDirect
Microelectronic Engineering journal homepage: www.elsevier.com/locate/mee
Electroluminescence, charge trapping and quenching in Eu implantes SiO2–Si structures S. Tyagulskiy a, I. Tyagulskyy a, A. Nazarov a,*, V. Lysenko a, L. Rebohle b, J. Lehmann b, W. Skorupa b a b
Lashkaryov Institute of Semiconductor Physics, NASU, Prospekt nauki 41, 03028 Kyiv, Ukraine Institut für Ionenstrahlphysik und Materialforschung, Forschungszentrum Dresden-Rossendorf e.V., Dresden, Germany
a r t i c l e
i n f o
Article history: Received 2 March 2009 Received in revised form 3 March 2009 Accepted 3 March 2009 Available online 13 March 2009 Keywords: Silicon dioxide Europium Electroluminescence
a b s t r a c t This paper reports an analysis of the electroluminescence (EL) spectra changing, charge trapping and EL quenching during operation of the multicolor Eu implanted metal-oxide-silicon light-emitting devices (MOSLEDs). The nature of the changing of the light-emitting color in the MOSLED is discussed. It is shown that the EL life time of the Eu implanted MOSLED is considerably longer than that of high-efficiency MOSLEDs with Tb and Ge implanted oxide. It is demonstrated that a reduced EL intensity, enhanced negative charge trapping and a good EL stability are associated with enhanced clustering in the Eu implanted oxide during high-temperature furnace annealing. The comparison with the operation of the MOSLED fabricated by using the flash lamp annealing technique is performed. Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction Metal-oxide-silicon (MOS) light-emitting devices (LEDs) with Eu implanted oxide show the possibility to emit light with different colors (from blue to red one) at different applied electric fields or currents [1]. However, the electroluminescent intensity (ELI) and life time of such MOSLEDs are not enough if compared with III–V light emitters. To overcome these shortcomings a deep study of charge trapping in the dielectric and electrical degradation processes in the device is necessary. This work studies the features of charge trapping in Eu implanted oxide with following high-temperature furnace (FA) or flash lamp annealing (FLA) and their connections with ELI. 2. Experimental In this work SiO2/n–Si structures implanted by Eu+ ions into the middle part of the oxide with a thickness of 100 nm have been used. The maximal concentration of the Eu impurity in the oxide, as calculated with the TRIM software, corresponds to values from 0.1 to 1.5 at.%. After implantation the samples were subjected to FA at 900 °C for 30 min in nitrogen ambient. Some samples were treated by FLA at 1000 °C for 20 ms. In order to fabricate devices and to retard the electrical break-down the SiO2 was covered with a low-temperature SiON layer with a thickness of 100 nm [2]. Indium tin oxide (ITO) was used as a semi-transparent gate * Corresponding author. Tel./fax: +380 44 5256177. E-mail address: [email protected] (A. Nazarov). 0167-9317/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.mee.2009.03.034
electrode. The experiments were performed with a positive voltage applied to the gate which corresponds to electron injection from the Si substrate into the dielectric. The EL spectra were measured with a constant current regime. The EL signal was recorded at room temperature in the wavelength range of 300–750 nm. The charge trapping during the EL excitation was studied by the change of the applied voltage to the structure under constant current injection (DVCC) [3]. The change of the intensity of the EL lines during operation of the device was studied by measuring consecutive EL spectra at a high injected current density (J = 1 103 A/cm2) followed by an analysis of their composition. The current–voltage (I–V) characteristics of the structures were measured in a joint cycle with the EL intensity at a fixed wavelength vs. the applied voltage. The EL decay time was measured by a multichannel scaler under constant voltage pulses. 3. Results and discussion 3.1. EL spectra The EL spectra of the Eu implanted MOSLED with different Eu concentration and subjected to FA at 900 °C and FLA treatments are presented in Fig. 1. Narrow peaks at 573, 590, 618 and 659 nm are attributed to 4f6D0–7Fj (j = 0, 1, 2, 3) intrashell transitions of Eu3+ [4], whose spectral position depends only weekly on the host material. The broad peaks in the range of 410–470 nm can be attributed to a 4f65d–4f7 transition of Eu2+ [5], whose spectral position strongly depends on the crystalline field of the host matrix.
S. Tyagulskiy et al. / Microelectronic Engineering 86 (2009) 1954–1956
1955
The dependence of ELI on J for 618 and 460 nm lines (not shown here) can be described by the standard expression for steady state condition [8]
ELI rsJ=q ¼ ; ELIMAX 1 þ rsJ=q
ð1Þ
where ELIMAX, r and s are the saturated EL intensity, the excitation cross-section, and the total life time of an excited level, correspondingly. Using the total life time, obtained from decay time experiments, the excitation cross-section for the EL line at 618 nm was estimated as 3.2 1016 cm2. 3.2. Transformation of the EL spectra and quenching of the EL under high electron injection levels
Fig. 1. EL spectra of the MOSLED as a function of the implanted Eu concentration and the type of used annealing. The FA was performed at 900 °C for 2 30 min; the FLA – at 1000 °C for 2 20 ms. Inset: intensity of the main EL lines vs. Eu concentration.
Fig. 2 depicts the dependence of the EL intensity of the main spectral lines (410, 460 and 618 nm) on the exciting current density. The intensity of the red (618 nm) line and the blue line (410 nm) distinctly changes with an increase of the current density. At a current density smaller than 0.2 A/cm2 the red line is dominant, whereas at a current density higher than that value the blue line is more intense. Thus, by changing the current in the device we can change a color of the light emission. The I–V characteristic, measured simultaneously with the EL-I dependence and presented in Fig. 2, allows us to clarify that the EL in the MOSLED is observed in the high-field electron injection regime, which corresponds to the Fowler–Nordheim electron tunneling through a triangle barrier. Additionally, Fig. 2 shows that changing of the current density from 1 104 to 2 A/cm2 modifies the electric field inside of the SiO2 from 8 106 to 1.2 107 V/cm. The average energy of hot electrons under such electric fields in the thick SiO2 changes in the range of 3.5–6 eV [6], but electrons from the high energy tail of the electron energy distribution can reach an energy up to 15 eV at 9.7 106 V/cm [7]. The increase of the average energy of hot electrons in the SiO2 enhances the EL intensity of the blue lines (410 and 460 nm) of the studied spectrum, but the appearance of hot electrons with a high energy results in degradation phenomena in the implanted dioxide.
Fig. 2. EL intensity of the MOSLED with 0.1% Eu, measured at 618, 460 and 410 nm as function of the injected current density. The dash dot curve shows current density vs. electric field in SiO2.
As there are hot electrons with high energies a change of the EL spectra is observed under operation of the MOSLED. In order to separate the EL lines in the range of 390–525 nm we performed a peak fitting analysis of the obtained spectra and extracted the amplitudes of the separate EL lines. The dependencies of the ELI of the main EL lines (410, 460 and 618 nm) and the changing of the constant current voltage applied to the device for MOSLEDs annealed at 900 °C are presented in Fig. 3a and b, respectively. All observed lines for the FA samples increase their intensity with the operation time which is accompanied by an increase of the operation voltage (Fig. 3b), that corresponds to a negative charge trapping of 1.4 1012 cm2 inside of the dielectric for injected
Fig. 3. The EL intensity at 618, 460 and 410 nm (a) and the VCC (b) as a function of the injection charge for FA and FLA Eu implanted MOSLEDs. Density of the injection current is 1 103 A/cm2.
1956
S. Tyagulskiy et al. / Microelectronic Engineering 86 (2009) 1954–1956
charges up to 8 1020 e/cm2. In our previous paper [9] it was shown that the Eu implanted oxide reveals electron trapping in a wide range of the injection charge (from 1 1014 to 1 1020 e/ cm2), which was linked with the enhanced clustering of Eu oxides and capability of Eu to create low valency oxides such as EuO and Eu3O4. It was suggested that enhanced clustering of Eu related oxides resulted in the generation of dangling and strained bonds capable of electron trapping in the SiO2 matrix in large concentrations. It should be noted that quenching of the main red line (618 nm) of the Eu EL for FA samples is observed at considerably larger injection charges than in case of the high-efficiency Tb implanted MOSLEDs [10]. To characterize the quenching probability the quenching cross-section (rq) was introduced [11]. This amount is determined from the dependence of the ELI vs. the injection charge (Qinj)
ELI ¼ ELIMAX expðrq Q inj Þ;
ð2Þ
and is directly linked with the quenching time (sq) by the following expression: rq = q/sq J, where J is the current density. Calculated magnitudes for the quenching cross-section of the main EL lines of the Eu implanted oxide such as 410, 460 and 618 nm are 6.2 1021, 4.0 1021 and 9.0 1022 cm2, correspondingly. These values are notably smaller than those obtained for the Tb implanted MOSLED (8 1021 cm2 for the 545 nm line) and the Ge implanted MOSLED (4.8 1020 cm2 for the 400 nm line) [11]. This underlines the increased stability of the Eu implanted MOSLED regarding to EL quenching. Analysis of Fig. 3a and b demonstrates the correlation of the EL quenching with negative charge trapping in the bulk of the SiO2, which can be associated both with the destruction of the LCs [12] and with negative charging of the luminescent clusters, resulting in a reduced excitation of the RE impurities located inside of the RE oxide clusters. 3.3. FLA effect on intensity and quenching of the EL To increase the EL intensity and decrease the negative charge trapping in the dielectric of the Eu implanted multicolor MOSLED it is necessary to form the dielectric layer with small sizes of the Eu oxide nanoclusters to secure the excitation of a maximal number of the RE impurities and weaken electron scattering on defect surroundings of the nanoclusters. To provide such a kind of SiO2 the FLA was used in the work. It was shown that such treatment ensures a Eu oxide nanoclusters size near 2 nm [9]. The EL spectrum of such devices is presented in Fig. 1. For lines of 618 nm and of 460 nm a 10-fold and fivefold increase of the EL intensity is observed, respectively. The excitation cross-section for the 618 nm line also increases and reaches a value of 2.6 1015 cm2 which is comparable with the excitation cross-section for the 545 nm line in the high-effective Tb implanted MOSLEDs [10].
It should be noted that for the FLA devices a start of EL quenching is shifted to smaller injection charge, and the EL quenching has a more complicated two step shape. The quenching cross-sections for the first and second steps quenching of 618 nm line are ð2Þ 21 rð1Þ cm2 and rq = 1.2 1021 cm2, respectively. q = 5.0 10 During the first step of the quenching a negative charge trapping is observed, but during the second one a positive charge is trapped inside of the dielectric (Fig. 3b). The changing of the constant current voltage on the second step of the quenching is too small to be explained by a reduction of the ELI caused by the decrease of the electric field inside of the SiO2. One suggested that positive charge trapping could be associated with E0 -centre generation with oxygen diffusion for the chemical reaction of Eu to form EuO and Eu2O3 oxides as following: þ hot::electron
þ
2 BSi—O—SiB þ Eu þ h ! BSi SiB þ Eu2þ O :
Actually, for high injected charges (more than 4 1020 e/cm2) an increase of ELI for 410 and 460 nm lines is observed (Fig. 3b). 4. Conclusions The multicolor Eu implanted MOSLEDs with an additional oxinitride layer furnace annealed at 900 °C demonstrate a long life time in comparison with other RE implanted MOSLEDs, but a lower EL intensity of the main EL lines. The study of the EL spectrum and the constant current voltage change during the MOSLED operation allowed us to clarify the EL quenching of all main luminescent lines in the visible range of the spectra and to find a correlation between the EL quenching and negative charge trapping in the bulk of the dielectric. The suggested method of estimating the EL quenching probability by employing the quenching cross-section demonstrated simplicity and convenience for the comparison of the different EL quenching processes. Whereas employing the FLA treatment increases considerably the EL intensity of the main lines of the Eu implanted MOSLED, the life time of this device insignificantly decreases. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]
S. Prucnal, J.M. Sun, W. Skorupa, M. Helm, Appl. Phys. Lett. 90 (2007) 181121. J.M. Sun, L. Rebohle, S. Prucnal, et al., Appl. Phys. Lett. 92 (2008) 071103. A.N. Nazarov, T. Gebel, L. Rebohle, et al., J. Appl. Phys. 94 (2003) 4440. U. Hömmerich, Ei Ei Nyein, D.S. Lee, et al., Mater. Sci. Eng. B105 (2003) 91. S.A. Studenikin, M. Cocivera, Thin Solid Films 394 (2001) 264. D.J. DiMaria, M.V. Fischetti, M. Arienzo, E. Tierney, J. Appl. Phys. 60 (1986) 1719. D.J. DiMaria, E. Cartier, D. Arnold, J. Appl. Phys. 73 (1993) 3367. F. Priolo, C.D. Presti, G. Franzo, et al., Phys. Rev. B 73 (2006) 113302. A.N. Nazarov, I.P. Tyagulskii, S.I. Tyagulskii et al., Physica E, in press J.M. Sun, W. Skorupa, T. Dekorsy, et al., J. Appl. Phys. 97 (2005) 123513. A. Nazarov, I. Osiyuk, I. Tyagulskii, et al., J. Lumin. 121 (2006) 213. A.N. Nazarov, I.N. Osiyuk, J.M. Sun, et al., Appl. Phys. B87 (2007) 129.
Contents lists available at ScienceDirect
Microelectronic Engineering journal homepage: www.elsevier.com/locate/mee
Electroluminescence, charge trapping and quenching in Eu implantes SiO2–Si structures S. Tyagulskiy a, I. Tyagulskyy a, A. Nazarov a,*, V. Lysenko a, L. Rebohle b, J. Lehmann b, W. Skorupa b a b
Lashkaryov Institute of Semiconductor Physics, NASU, Prospekt nauki 41, 03028 Kyiv, Ukraine Institut für Ionenstrahlphysik und Materialforschung, Forschungszentrum Dresden-Rossendorf e.V., Dresden, Germany
a r t i c l e
i n f o
Article history: Received 2 March 2009 Received in revised form 3 March 2009 Accepted 3 March 2009 Available online 13 March 2009 Keywords: Silicon dioxide Europium Electroluminescence
a b s t r a c t This paper reports an analysis of the electroluminescence (EL) spectra changing, charge trapping and EL quenching during operation of the multicolor Eu implanted metal-oxide-silicon light-emitting devices (MOSLEDs). The nature of the changing of the light-emitting color in the MOSLED is discussed. It is shown that the EL life time of the Eu implanted MOSLED is considerably longer than that of high-efficiency MOSLEDs with Tb and Ge implanted oxide. It is demonstrated that a reduced EL intensity, enhanced negative charge trapping and a good EL stability are associated with enhanced clustering in the Eu implanted oxide during high-temperature furnace annealing. The comparison with the operation of the MOSLED fabricated by using the flash lamp annealing technique is performed. Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction Metal-oxide-silicon (MOS) light-emitting devices (LEDs) with Eu implanted oxide show the possibility to emit light with different colors (from blue to red one) at different applied electric fields or currents [1]. However, the electroluminescent intensity (ELI) and life time of such MOSLEDs are not enough if compared with III–V light emitters. To overcome these shortcomings a deep study of charge trapping in the dielectric and electrical degradation processes in the device is necessary. This work studies the features of charge trapping in Eu implanted oxide with following high-temperature furnace (FA) or flash lamp annealing (FLA) and their connections with ELI. 2. Experimental In this work SiO2/n–Si structures implanted by Eu+ ions into the middle part of the oxide with a thickness of 100 nm have been used. The maximal concentration of the Eu impurity in the oxide, as calculated with the TRIM software, corresponds to values from 0.1 to 1.5 at.%. After implantation the samples were subjected to FA at 900 °C for 30 min in nitrogen ambient. Some samples were treated by FLA at 1000 °C for 20 ms. In order to fabricate devices and to retard the electrical break-down the SiO2 was covered with a low-temperature SiON layer with a thickness of 100 nm [2]. Indium tin oxide (ITO) was used as a semi-transparent gate * Corresponding author. Tel./fax: +380 44 5256177. E-mail address: [email protected] (A. Nazarov). 0167-9317/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.mee.2009.03.034
electrode. The experiments were performed with a positive voltage applied to the gate which corresponds to electron injection from the Si substrate into the dielectric. The EL spectra were measured with a constant current regime. The EL signal was recorded at room temperature in the wavelength range of 300–750 nm. The charge trapping during the EL excitation was studied by the change of the applied voltage to the structure under constant current injection (DVCC) [3]. The change of the intensity of the EL lines during operation of the device was studied by measuring consecutive EL spectra at a high injected current density (J = 1 103 A/cm2) followed by an analysis of their composition. The current–voltage (I–V) characteristics of the structures were measured in a joint cycle with the EL intensity at a fixed wavelength vs. the applied voltage. The EL decay time was measured by a multichannel scaler under constant voltage pulses. 3. Results and discussion 3.1. EL spectra The EL spectra of the Eu implanted MOSLED with different Eu concentration and subjected to FA at 900 °C and FLA treatments are presented in Fig. 1. Narrow peaks at 573, 590, 618 and 659 nm are attributed to 4f6D0–7Fj (j = 0, 1, 2, 3) intrashell transitions of Eu3+ [4], whose spectral position depends only weekly on the host material. The broad peaks in the range of 410–470 nm can be attributed to a 4f65d–4f7 transition of Eu2+ [5], whose spectral position strongly depends on the crystalline field of the host matrix.
S. Tyagulskiy et al. / Microelectronic Engineering 86 (2009) 1954–1956
1955
The dependence of ELI on J for 618 and 460 nm lines (not shown here) can be described by the standard expression for steady state condition [8]
ELI rsJ=q ¼ ; ELIMAX 1 þ rsJ=q
ð1Þ
where ELIMAX, r and s are the saturated EL intensity, the excitation cross-section, and the total life time of an excited level, correspondingly. Using the total life time, obtained from decay time experiments, the excitation cross-section for the EL line at 618 nm was estimated as 3.2 1016 cm2. 3.2. Transformation of the EL spectra and quenching of the EL under high electron injection levels
Fig. 1. EL spectra of the MOSLED as a function of the implanted Eu concentration and the type of used annealing. The FA was performed at 900 °C for 2 30 min; the FLA – at 1000 °C for 2 20 ms. Inset: intensity of the main EL lines vs. Eu concentration.
Fig. 2 depicts the dependence of the EL intensity of the main spectral lines (410, 460 and 618 nm) on the exciting current density. The intensity of the red (618 nm) line and the blue line (410 nm) distinctly changes with an increase of the current density. At a current density smaller than 0.2 A/cm2 the red line is dominant, whereas at a current density higher than that value the blue line is more intense. Thus, by changing the current in the device we can change a color of the light emission. The I–V characteristic, measured simultaneously with the EL-I dependence and presented in Fig. 2, allows us to clarify that the EL in the MOSLED is observed in the high-field electron injection regime, which corresponds to the Fowler–Nordheim electron tunneling through a triangle barrier. Additionally, Fig. 2 shows that changing of the current density from 1 104 to 2 A/cm2 modifies the electric field inside of the SiO2 from 8 106 to 1.2 107 V/cm. The average energy of hot electrons under such electric fields in the thick SiO2 changes in the range of 3.5–6 eV [6], but electrons from the high energy tail of the electron energy distribution can reach an energy up to 15 eV at 9.7 106 V/cm [7]. The increase of the average energy of hot electrons in the SiO2 enhances the EL intensity of the blue lines (410 and 460 nm) of the studied spectrum, but the appearance of hot electrons with a high energy results in degradation phenomena in the implanted dioxide.
Fig. 2. EL intensity of the MOSLED with 0.1% Eu, measured at 618, 460 and 410 nm as function of the injected current density. The dash dot curve shows current density vs. electric field in SiO2.
As there are hot electrons with high energies a change of the EL spectra is observed under operation of the MOSLED. In order to separate the EL lines in the range of 390–525 nm we performed a peak fitting analysis of the obtained spectra and extracted the amplitudes of the separate EL lines. The dependencies of the ELI of the main EL lines (410, 460 and 618 nm) and the changing of the constant current voltage applied to the device for MOSLEDs annealed at 900 °C are presented in Fig. 3a and b, respectively. All observed lines for the FA samples increase their intensity with the operation time which is accompanied by an increase of the operation voltage (Fig. 3b), that corresponds to a negative charge trapping of 1.4 1012 cm2 inside of the dielectric for injected
Fig. 3. The EL intensity at 618, 460 and 410 nm (a) and the VCC (b) as a function of the injection charge for FA and FLA Eu implanted MOSLEDs. Density of the injection current is 1 103 A/cm2.
1956
S. Tyagulskiy et al. / Microelectronic Engineering 86 (2009) 1954–1956
charges up to 8 1020 e/cm2. In our previous paper [9] it was shown that the Eu implanted oxide reveals electron trapping in a wide range of the injection charge (from 1 1014 to 1 1020 e/ cm2), which was linked with the enhanced clustering of Eu oxides and capability of Eu to create low valency oxides such as EuO and Eu3O4. It was suggested that enhanced clustering of Eu related oxides resulted in the generation of dangling and strained bonds capable of electron trapping in the SiO2 matrix in large concentrations. It should be noted that quenching of the main red line (618 nm) of the Eu EL for FA samples is observed at considerably larger injection charges than in case of the high-efficiency Tb implanted MOSLEDs [10]. To characterize the quenching probability the quenching cross-section (rq) was introduced [11]. This amount is determined from the dependence of the ELI vs. the injection charge (Qinj)
ELI ¼ ELIMAX expðrq Q inj Þ;
ð2Þ
and is directly linked with the quenching time (sq) by the following expression: rq = q/sq J, where J is the current density. Calculated magnitudes for the quenching cross-section of the main EL lines of the Eu implanted oxide such as 410, 460 and 618 nm are 6.2 1021, 4.0 1021 and 9.0 1022 cm2, correspondingly. These values are notably smaller than those obtained for the Tb implanted MOSLED (8 1021 cm2 for the 545 nm line) and the Ge implanted MOSLED (4.8 1020 cm2 for the 400 nm line) [11]. This underlines the increased stability of the Eu implanted MOSLED regarding to EL quenching. Analysis of Fig. 3a and b demonstrates the correlation of the EL quenching with negative charge trapping in the bulk of the SiO2, which can be associated both with the destruction of the LCs [12] and with negative charging of the luminescent clusters, resulting in a reduced excitation of the RE impurities located inside of the RE oxide clusters. 3.3. FLA effect on intensity and quenching of the EL To increase the EL intensity and decrease the negative charge trapping in the dielectric of the Eu implanted multicolor MOSLED it is necessary to form the dielectric layer with small sizes of the Eu oxide nanoclusters to secure the excitation of a maximal number of the RE impurities and weaken electron scattering on defect surroundings of the nanoclusters. To provide such a kind of SiO2 the FLA was used in the work. It was shown that such treatment ensures a Eu oxide nanoclusters size near 2 nm [9]. The EL spectrum of such devices is presented in Fig. 1. For lines of 618 nm and of 460 nm a 10-fold and fivefold increase of the EL intensity is observed, respectively. The excitation cross-section for the 618 nm line also increases and reaches a value of 2.6 1015 cm2 which is comparable with the excitation cross-section for the 545 nm line in the high-effective Tb implanted MOSLEDs [10].
It should be noted that for the FLA devices a start of EL quenching is shifted to smaller injection charge, and the EL quenching has a more complicated two step shape. The quenching cross-sections for the first and second steps quenching of 618 nm line are ð2Þ 21 rð1Þ cm2 and rq = 1.2 1021 cm2, respectively. q = 5.0 10 During the first step of the quenching a negative charge trapping is observed, but during the second one a positive charge is trapped inside of the dielectric (Fig. 3b). The changing of the constant current voltage on the second step of the quenching is too small to be explained by a reduction of the ELI caused by the decrease of the electric field inside of the SiO2. One suggested that positive charge trapping could be associated with E0 -centre generation with oxygen diffusion for the chemical reaction of Eu to form EuO and Eu2O3 oxides as following: þ hot::electron
þ
2 BSi—O—SiB þ Eu þ h ! BSi SiB þ Eu2þ O :
Actually, for high injected charges (more than 4 1020 e/cm2) an increase of ELI for 410 and 460 nm lines is observed (Fig. 3b). 4. Conclusions The multicolor Eu implanted MOSLEDs with an additional oxinitride layer furnace annealed at 900 °C demonstrate a long life time in comparison with other RE implanted MOSLEDs, but a lower EL intensity of the main EL lines. The study of the EL spectrum and the constant current voltage change during the MOSLED operation allowed us to clarify the EL quenching of all main luminescent lines in the visible range of the spectra and to find a correlation between the EL quenching and negative charge trapping in the bulk of the dielectric. The suggested method of estimating the EL quenching probability by employing the quenching cross-section demonstrated simplicity and convenience for the comparison of the different EL quenching processes. Whereas employing the FLA treatment increases considerably the EL intensity of the main lines of the Eu implanted MOSLED, the life time of this device insignificantly decreases. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]
S. Prucnal, J.M. Sun, W. Skorupa, M. Helm, Appl. Phys. Lett. 90 (2007) 181121. J.M. Sun, L. Rebohle, S. Prucnal, et al., Appl. Phys. Lett. 92 (2008) 071103. A.N. Nazarov, T. Gebel, L. Rebohle, et al., J. Appl. Phys. 94 (2003) 4440. U. Hömmerich, Ei Ei Nyein, D.S. Lee, et al., Mater. Sci. Eng. B105 (2003) 91. S.A. Studenikin, M. Cocivera, Thin Solid Films 394 (2001) 264. D.J. DiMaria, M.V. Fischetti, M. Arienzo, E. Tierney, J. Appl. Phys. 60 (1986) 1719. D.J. DiMaria, E. Cartier, D. Arnold, J. Appl. Phys. 73 (1993) 3367. F. Priolo, C.D. Presti, G. Franzo, et al., Phys. Rev. B 73 (2006) 113302. A.N. Nazarov, I.P. Tyagulskii, S.I. Tyagulskii et al., Physica E, in press J.M. Sun, W. Skorupa, T. Dekorsy, et al., J. Appl. Phys. 97 (2005) 123513. A. Nazarov, I. Osiyuk, I. Tyagulskii, et al., J. Lumin. 121 (2006) 213. A.N. Nazarov, I.N. Osiyuk, J.M. Sun, et al., Appl. Phys. B87 (2007) 129.