基于含三價稀土離子的氧化物薄膜的硅基電致發(fā)光器件
發(fā)布時間：2018-07-28 18:15
【摘要】：眾所周知,作為微電子工業(yè)基礎(chǔ)材料的硅是一種間接帶隙半導(dǎo)體,發(fā)光效率非常低,這嚴(yán)重限制了硅基光電集成技術(shù)的發(fā)展。因此,需要利用其它發(fā)光材料制備用于硅基光電集成的光源。稀土離子具有特殊的電子結(jié)構(gòu),其發(fā)光具有色純度高、穩(wěn)定性好、受基體和外界環(huán)境影響小等特點,這使得人們以很大的熱情研究稀土離子發(fā)光。稀土離子的有效激發(fā)通常需要適當(dāng)?shù)幕w材料,而氧化物便是相當(dāng)理想的基體材料,其中包括氧化物半導(dǎo)體。稀土摻雜的氧化物薄膜的制備工藝與集成電路制造工藝相兼容,因此,實現(xiàn)硅基稀土摻雜氧化物薄膜電致發(fā)光器件,對于拓寬稀土離子發(fā)光的應(yīng)用范圍和發(fā)展硅基光電集成所需的光源具有重要意義。本文詳細(xì)研究了以摻入不同稀土離子的TiO2薄膜為發(fā)光層的硅基發(fā)光器件的電致發(fā)光及其物理機制。此外,還制備了禁帶寬度相對較小(屬于半導(dǎo)體范疇)的Tb4O7薄膜為發(fā)光層的MOS器件,實現(xiàn)了Tb3+離子的特征電致發(fā)光。本文取得的主要創(chuàng)新成果如下：(1)利用射頻濺射法,在重?fù)絧型硅片(p+-Si)上沉積Eu含量不同(0.8%和1.2%)的TiO2 (TiO2:Eu)薄膜,隨后進(jìn)行550或650 ℃的熱處理。在此基礎(chǔ)上,制備了基于TiO2:Eu/p+-Si異質(zhì)結(jié)的器件,實現(xiàn)其電致發(fā)光。研究發(fā)現(xiàn),與Eu3+相關(guān)的紅色發(fā)光是由TiO2基體中的氧空位作為敏化中心向鄰近的Eu3+離子傳遞的能量所激發(fā)的,而該過程減弱了與氧空位相關(guān)的可見發(fā)光。TiO2薄膜中更高的Eu含量和TiO2:Eu薄膜的更高熱處理溫度均能夠促進(jìn)從TiO2基體向Eu3+離子的能量傳遞。因此,通過提高TiO2薄膜中的Eu含量和TiO2：Eu薄膜的熱處理溫度,可以使器件的電致發(fā)光從氧空位相關(guān)的發(fā)光為主轉(zhuǎn)變?yōu)榕cEu相關(guān)的發(fā)光為主,從而展現(xiàn)出不同的發(fā)光顏色。(2)利用射頻濺射法,在p+-Si上沉積不同Tm含量的TiO2薄膜,隨后進(jìn)行氧氣氛下650℃熱處理。在此基礎(chǔ)上,制備基于TiO2:Tm/p+-Si異質(zhì)結(jié)的器件,實現(xiàn)了源自TiO2基體的可見發(fā)光和源自Tm3+離子的近紅外電致發(fā)光。研究發(fā)現(xiàn),基于TiO2：Tm(0.9%)薄膜的器件發(fā)射出與Tm3+離子相關(guān)的～800 nm發(fā)光,同時與TiO2基體相關(guān)的可見發(fā)光顯著減弱,表明與Tm3+相關(guān)的發(fā)光是由TiO2基體向Tm3+離子傳遞的能量激發(fā)的。隨著TiO2：Tm薄膜中的Tm含量的增加,上述可見和近紅外發(fā)光均顯著增強,可歸因于摻入更高含量的Tm3+在TiO2基體中引入了更多氧空位。此外,在TiO2:Tm(1.6%)薄膜中共摻F后,器件的可見和近紅外發(fā)光被完全抑制。由于離子半徑相近,摻入的F-離子傾向于占據(jù)氧空位的位置。這從側(cè)面證實了TiO2基體與Tm3+離子之間的能量傳遞是通過氧空位作為敏化中心進(jìn)行的。(3)利用射頻濺射法,在p+-Si上沉積共摻Fe和Er的Ti02[Ti02:(Fe,Er)]薄膜,隨后進(jìn)行氧氣氛下550℃熱處理。在此基礎(chǔ)上,制備了基于Ti02:(Fe, Er)/p+一Si異質(zhì)結(jié)的器件。在正向偏壓下,該器件僅發(fā)射出與Er3+離子相關(guān)的～1540nm近紅外光。研究表明,共摻Fe抑制了與Er3+離子和TiO2基體中的氧空位相關(guān)的可見發(fā)光,而與Er3+離子相關(guān)的～1540 nm發(fā)光被一定程度地增強。Fe雜質(zhì)在TiO2禁帶中引入能級,作為電子和空穴的復(fù)合中心。載流子通過與Fe相關(guān)的能級輔助的間接復(fù)合所釋放的能量僅能激發(fā)電子從Er3+離子的基態(tài)躍遷到次低的激發(fā)態(tài),在隨后的退激發(fā)過程中,僅發(fā)射出～1540 nm的近紅外發(fā)光。(4)在重?fù)絥型硅片(n+-Si)上先通過干法熱氧化形成～10 nm的SiO2薄膜,然后利用射頻濺射法沉積摻入不同稀土離子的TiO2(TiO2:RE,RE=Eu、Er、Tm或Nd)薄膜,隨后進(jìn)行氧氣氛下700℃熱處理。在此基礎(chǔ)上,制備了ITO/TiO2:RE/SiO2/Si結(jié)構(gòu)的器件。在低于10 V的直流偏壓下,實現(xiàn)了該類器件的紅色、綠色、藍(lán)色和近紅外的電致發(fā)光,它們源自于TiO2薄膜中的各種稀土離子受碰撞激發(fā)后的自發(fā)輻射。分析指出,當(dāng)在ITO電極上施加足夠高的正向電壓時,n+-Si中的電子通過缺陷輔助隧穿機制進(jìn)入SiO2層的導(dǎo)帶,在電場驅(qū)動下,電子落入Ti02：RE層的導(dǎo)帶,獲得了相當(dāng)于SiO2與TiO2導(dǎo)帶勢能差的能量(～4 eV),從而成為熱電子。這些熱電子碰撞激發(fā)TiO2薄膜中的RE3+離子,從而導(dǎo)致RE3+離子的特征發(fā)光。(5)利用射頻濺射法,分別在重?fù)搅缀椭負(fù)脚鸬墓枰r底(n+-Si和p+-Si)上沉積Tb4O7薄膜,隨后進(jìn)行氬氣氛下900℃熱處理。在此基礎(chǔ)上,制備以Tb4O7薄膜為發(fā)光層的MOS器件,實現(xiàn)了源自Tb3+離子內(nèi)4f躍遷的綠色電致發(fā)光,其開啟電壓低于10 V。通過分析器件的電流-電壓特性和電致發(fā)光譜,指出n+-Si(或p+～Si)中的電子(空穴)通過缺陷輔助隧穿機制進(jìn)入Tb4O7的導(dǎo)帶(價帶),并在電場作用下加速,形成熱電子(空穴),它們碰撞激發(fā)Tb4O7薄膜中固有的Tb3+離子,從而導(dǎo)致Tb3+離子的特征綠色發(fā)光。
[Abstract]:It is well known that silicon, an indirect band gap semiconductor, is an indirect band gap semiconductor with low luminescence efficiency, which seriously restricts the development of silicon based photoelectric integration technology. Therefore, other luminescent materials need to be used to prepare light sources for silicon based photoelectric integration. Rare earth ions have special electronic structures and their luminescence has color purity. It is characterized by high stability and small influence on the matrix and the external environment. This makes people study the luminescence of rare earth ions with great enthusiasm. The effective excitation of rare earth ions usually requires appropriate matrix material, and oxide is quite ideal matrix material, including oxide semiconductor. Therefore, the realization of silicon based rare earth doped oxide thin film electroluminescent devices is of great significance for widening the application range of rare earth ion luminescence and developing the light source required for silicon based photoelectric integration. In this paper, the silicon based luminescence of TiO2 films doped with different rare earth ions as the luminescent layer is studied in detail. The electroluminescence and the physical mechanism of the device are also made. In addition, the Tb4O7 thin film with a relatively small gap (belonging to the semiconductor category) is also prepared as the MOS device of the luminescent layer, and the characteristic electroluminescence of the Tb3+ ions is realized. The main achievements of this paper are as follows: (1) the content of Eu in the heavily doped P silicon wafer (p+-Si) is not deposited by radio frequency sputtering. The TiO2 (TiO2:Eu) film (0.8% and 1.2%) was followed by heat treatment at 550 or 650 C. On this basis, a device based on TiO2:Eu/p+-Si heterojunction was prepared to realize its electroluminescence. It was found that the red luminescence related to Eu3+ was excited by the oxygen vacancy in the TiO2 matrix as the energy transfer from the sensitization center to the adjacent Eu3+ ion. This process reduces the higher Eu content in the visible luminescent.TiO2 film related to the oxygen vacancy and the higher heat treatment temperature of the TiO2:Eu film, which can promote the energy transfer from the TiO2 matrix to the Eu3+ ion. Therefore, the electroluminescence of the device can be induced by increasing the Eu content in the TiO2 film and the heat treatment temperature of the TiO2:Eu film. The oxygen vacancy related luminescence mainly changed to Eu related luminescence, which showed different luminescence colors. (2) TiO2 films with different Tm content were deposited on p+-Si by radio frequency sputtering and then heated at 650 C under oxygen atmosphere. On this basis, the devices based on TiO2:Tm/p+-Si heterojunction were prepared, and the TiO2 matrix was realized. The visible luminescence and near infrared electroluminescence derived from Tm3+ ions have been found. It is found that the devices based on TiO2:Tm (0.9%) films emit a 800 nm luminescence associated with Tm3+ ions, while the visible luminescence associated with the TiO2 matrix decreases significantly, indicating that the luminescence related to the Tm3+ is excited by the energy transferred from the TiO2 matrix to the Tm3+ ions. The increase in the content of Tm in the 2:Tm film is significantly enhanced by the visible and near infrared luminescence, which is attributable to the introduction of more oxygen vacancies in the TiO2 matrix with a higher content of Tm3+. In addition, the visible and near infrared luminescence of the TiO2:Tm (1.6%) thin film is completely suppressed after the incorporation of F in the TiO2:Tm film. As the ionic radius is similar, the doping of F- ions tilting. It is confirmed that the energy transfer between the TiO2 matrix and the Tm3+ ion is carried out by the oxygen vacancy as the sensitization center. (3) the Ti02[Ti02: (Fe, Er) Film Co doped with Fe and Er (Fe, Er)) is deposited on p+-Si by radio frequency sputtering, then the heat treatment at 550 C under the oxygen atmosphere. On this basis, the preparation of Ti0 is made. 2: (Fe, Er) /p+ Si heterojunction devices. Under positive bias, the device only emits the near infrared light to 1540nm related to Er3+ ions. The study shows that the co doping of Fe inhibits the visible luminescence associated with the oxygen vacancy in the Er3+ ions and TiO2 matrix, and the ~ 1540 nm luminescence related to the Er3+ ion is enhanced to a certain extent. The energy level is introduced in the band as the compound center of the electrons and holes. The energy released by the carrier assisted indirect recombination with the Fe related energy level can only stimulate the electron transition from the base state of the Er3+ ion to the sub low excited state. In the subsequent deactivation process, the emission of near infrared luminescence to 1540 nm is only emitted. (4) the N type silicon wafer (n+-Si) is heavily doped. The SiO2 thin film to 10 nm was formed by dry thermal oxidation, and then the TiO2 (TiO2:RE, RE=Eu, Er, Tm or Nd) films doped with different rare earth ions were deposited by radio frequency sputtering, then the heat treated at 700 C under oxygen atmosphere. On this basis, the ITO/TiO2:RE/SiO2/Si junction device was prepared. Under the DC bias of less than 10 V, this kind of device was realized. The red, green, blue and near infrared electroluminescence of the devices originate from the spontaneous emission of various rare earth ions in the TiO2 film after collisions. It is pointed out that when the positive voltage is high enough on the ITO electrode, the electrons in n+-Si enter the conduction band of the SiO2 layer through the defect assisted tunneling mechanism, and the electric field is driven by the electric field. The conduction band falling into the Ti02:RE layer obtained the energy equivalent to the potential energy difference between SiO2 and TiO2 (~ 4 eV) and became hot electrons. These thermo electron collisions stimulated the RE3+ ions in the TiO2 film, resulting in the characteristic luminescence of the RE3+ ions. (5) the deposition of phosphorus and boron doped silicon substrates (n+-Si and p+-Si) by radio frequency sputtering. Tb4O7 film is then heated at 900 C in argon atmosphere. On this basis, a MOS device with a Tb4O7 film as a luminescent layer is prepared, and the green electroluminescence from the 4f transition in the Tb3+ ion is realized. The opening voltage is lower than 10 V. through the current voltage characteristic and electroluminescence spectrum of the analysis device, and the electron (hole) in n+-Si (or p+ to Si) is pointed out. Through the defect assisted tunneling mechanism, the conduction band (valence band) of Tb4O7 is entered, and the thermal electrons (holes) are formed under the action of the electric field. They collide and stimulate the inherent Tb3+ ions in the Tb4O7 film, which leads to the characteristic green luminescence of the Tb3+ ions.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TN383.1;TB383.2
，
本文編號：2151191
[Abstract]:It is well known that silicon, an indirect band gap semiconductor, is an indirect band gap semiconductor with low luminescence efficiency, which seriously restricts the development of silicon based photoelectric integration technology. Therefore, other luminescent materials need to be used to prepare light sources for silicon based photoelectric integration. Rare earth ions have special electronic structures and their luminescence has color purity. It is characterized by high stability and small influence on the matrix and the external environment. This makes people study the luminescence of rare earth ions with great enthusiasm. The effective excitation of rare earth ions usually requires appropriate matrix material, and oxide is quite ideal matrix material, including oxide semiconductor. Therefore, the realization of silicon based rare earth doped oxide thin film electroluminescent devices is of great significance for widening the application range of rare earth ion luminescence and developing the light source required for silicon based photoelectric integration. In this paper, the silicon based luminescence of TiO2 films doped with different rare earth ions as the luminescent layer is studied in detail. The electroluminescence and the physical mechanism of the device are also made. In addition, the Tb4O7 thin film with a relatively small gap (belonging to the semiconductor category) is also prepared as the MOS device of the luminescent layer, and the characteristic electroluminescence of the Tb3+ ions is realized. The main achievements of this paper are as follows: (1) the content of Eu in the heavily doped P silicon wafer (p+-Si) is not deposited by radio frequency sputtering. The TiO2 (TiO2:Eu) film (0.8% and 1.2%) was followed by heat treatment at 550 or 650 C. On this basis, a device based on TiO2:Eu/p+-Si heterojunction was prepared to realize its electroluminescence. It was found that the red luminescence related to Eu3+ was excited by the oxygen vacancy in the TiO2 matrix as the energy transfer from the sensitization center to the adjacent Eu3+ ion. This process reduces the higher Eu content in the visible luminescent.TiO2 film related to the oxygen vacancy and the higher heat treatment temperature of the TiO2:Eu film, which can promote the energy transfer from the TiO2 matrix to the Eu3+ ion. Therefore, the electroluminescence of the device can be induced by increasing the Eu content in the TiO2 film and the heat treatment temperature of the TiO2:Eu film. The oxygen vacancy related luminescence mainly changed to Eu related luminescence, which showed different luminescence colors. (2) TiO2 films with different Tm content were deposited on p+-Si by radio frequency sputtering and then heated at 650 C under oxygen atmosphere. On this basis, the devices based on TiO2:Tm/p+-Si heterojunction were prepared, and the TiO2 matrix was realized. The visible luminescence and near infrared electroluminescence derived from Tm3+ ions have been found. It is found that the devices based on TiO2:Tm (0.9%) films emit a 800 nm luminescence associated with Tm3+ ions, while the visible luminescence associated with the TiO2 matrix decreases significantly, indicating that the luminescence related to the Tm3+ is excited by the energy transferred from the TiO2 matrix to the Tm3+ ions. The increase in the content of Tm in the 2:Tm film is significantly enhanced by the visible and near infrared luminescence, which is attributable to the introduction of more oxygen vacancies in the TiO2 matrix with a higher content of Tm3+. In addition, the visible and near infrared luminescence of the TiO2:Tm (1.6%) thin film is completely suppressed after the incorporation of F in the TiO2:Tm film. As the ionic radius is similar, the doping of F- ions tilting. It is confirmed that the energy transfer between the TiO2 matrix and the Tm3+ ion is carried out by the oxygen vacancy as the sensitization center. (3) the Ti02[Ti02: (Fe, Er) Film Co doped with Fe and Er (Fe, Er)) is deposited on p+-Si by radio frequency sputtering, then the heat treatment at 550 C under the oxygen atmosphere. On this basis, the preparation of Ti0 is made. 2: (Fe, Er) /p+ Si heterojunction devices. Under positive bias, the device only emits the near infrared light to 1540nm related to Er3+ ions. The study shows that the co doping of Fe inhibits the visible luminescence associated with the oxygen vacancy in the Er3+ ions and TiO2 matrix, and the ~ 1540 nm luminescence related to the Er3+ ion is enhanced to a certain extent. The energy level is introduced in the band as the compound center of the electrons and holes. The energy released by the carrier assisted indirect recombination with the Fe related energy level can only stimulate the electron transition from the base state of the Er3+ ion to the sub low excited state. In the subsequent deactivation process, the emission of near infrared luminescence to 1540 nm is only emitted. (4) the N type silicon wafer (n+-Si) is heavily doped. The SiO2 thin film to 10 nm was formed by dry thermal oxidation, and then the TiO2 (TiO2:RE, RE=Eu, Er, Tm or Nd) films doped with different rare earth ions were deposited by radio frequency sputtering, then the heat treated at 700 C under oxygen atmosphere. On this basis, the ITO/TiO2:RE/SiO2/Si junction device was prepared. Under the DC bias of less than 10 V, this kind of device was realized. The red, green, blue and near infrared electroluminescence of the devices originate from the spontaneous emission of various rare earth ions in the TiO2 film after collisions. It is pointed out that when the positive voltage is high enough on the ITO electrode, the electrons in n+-Si enter the conduction band of the SiO2 layer through the defect assisted tunneling mechanism, and the electric field is driven by the electric field. The conduction band falling into the Ti02:RE layer obtained the energy equivalent to the potential energy difference between SiO2 and TiO2 (~ 4 eV) and became hot electrons. These thermo electron collisions stimulated the RE3+ ions in the TiO2 film, resulting in the characteristic luminescence of the RE3+ ions. (5) the deposition of phosphorus and boron doped silicon substrates (n+-Si and p+-Si) by radio frequency sputtering. Tb4O7 film is then heated at 900 C in argon atmosphere. On this basis, a MOS device with a Tb4O7 film as a luminescent layer is prepared, and the green electroluminescence from the 4f transition in the Tb3+ ion is realized. The opening voltage is lower than 10 V. through the current voltage characteristic and electroluminescence spectrum of the analysis device, and the electron (hole) in n+-Si (or p+ to Si) is pointed out. Through the defect assisted tunneling mechanism, the conduction band (valence band) of Tb4O7 is entered, and the thermal electrons (holes) are formed under the action of the electric field. They collide and stimulate the inherent Tb3+ ions in the Tb4O7 film, which leads to the characteristic green luminescence of the Tb3+ ions.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TN383.1;TB383.2
，
本文編號：2151191
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