本文關(guān)鍵詞：硅基自旋注入器件及其界面特性研究　出處：《蘭州大學(xué)》2016年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 自旋電子器件 自旋注入與探測 Hanle曲線 磁隧道結(jié) 氧化鉿

【摘要】：發(fā)展硅基自旋電子器件是當(dāng)今半導(dǎo)體自旋電子學(xué)應(yīng)用領(lǐng)域的研究熱點(diǎn)之一。本論文圍繞硅基自旋注入三端器件的研制為主線,重點(diǎn)開展了NiFe/HfO_2/Si磁隧道結(jié)的制備及其界面特性研究,以期開發(fā)新的硅基自旋電子器件。此外,還對(duì)Ge pMOSFET器件的制備及電學(xué)特性進(jìn)行了一些探索,為今后開發(fā)自旋晶體管積累經(jīng)驗(yàn)。(一)磁性電極NiFe薄膜的制備和特性研究1.以高摻n型Si為襯底,利用磁控濺射制備了不同厚度的NiFe薄膜,并對(duì)部分樣品進(jìn)行了退火處理,系統(tǒng)研究了樣品的面內(nèi)和面外磁各向異性與薄膜厚度之間的關(guān)系,以及不同條件退火對(duì)磁性能的影響,結(jié)果表明為了符合硅基自旋注入對(duì)磁性電極薄膜的要求,NiFe薄膜的厚度需控制在30 nm以內(nèi),并且退火溫度以250℃為佳;2.為了抑制NiFe薄膜中的Ni、Fe往Si襯底中擴(kuò)散,同時(shí)也為了形成隧道結(jié),在NiFe與Si之間插入了2 nm厚的HfO_2薄膜,并進(jìn)行了退火處理,研究了樣品退火前后的磁性能,并利用XPS測試和分析了NiFe薄膜的組分、化學(xué)鍵和擴(kuò)散情況,結(jié)果顯示HfO_2薄層的引入可部分抑制Ni、Fe往Si中擴(kuò)散,使得Al(22 nm)/NiFe(28 nm)/HfO_2(2 nm)/Si樣品經(jīng)250℃退火以后其飽和磁化強(qiáng)度提高了約80%,有利于硅基自旋注入;3.對(duì)CoFe薄膜的制備進(jìn)行了一些探索。(二)介質(zhì)層HfO_2超薄薄膜的制備及界面、電學(xué)特性研究1.分別采用(E-beam)和原子層沉積(ALD)技術(shù)在高摻n型Si襯底上制備了HfO_2超薄薄膜(厚度范圍0-5 nm),并利用XPS進(jìn)行了深度剖析,系統(tǒng)研究了Si上直接生長HfO_2薄膜的組分、化學(xué)鍵和擴(kuò)散情況,結(jié)果顯示ALD生長的HfO_2薄膜粗糙度較小,約0.10 nm,厚度控制精度較高,表面層符合化學(xué)配比,可能適合用于硅基自旋注入;2.研究了不同方法制備的Metal/HfO_2/n+-Si接觸隨HfO_2插層厚度(E-beam0-5nm或ALD 0-2.5 nm)變化的I-V特性,優(yōu)化了用于硅基自旋注入隧穿層的HfO_2薄膜的制備方案;3.研究了NiFe/HfO_2(0-2 nm)/p-Si接觸的I-V特性,探討了HfO_2插層對(duì)NiFe/Si肖特基勢壘高度的調(diào)制作用和機(jī)理,為今后轉(zhuǎn)向低摻雜濃度Si進(jìn)行自旋注入探路。(三)硅基自旋注入三端器件的研制和性能測試及分析1.根據(jù)前兩章的研究結(jié)果設(shè)計(jì)工藝流程,制備出了以NiFe/HfO_2/n+-Si磁隧道結(jié)為核心的硅基自旋注入三端器件,為了對(duì)比,采用相同的工藝參數(shù)也制備了NiFe/Al_2O_3/n+-Si三端器件,并對(duì)部分器件進(jìn)行了退火處理,測試了器件的電學(xué)特性(I-V特性)和自旋注入特性(Hanle曲線);結(jié)果顯示研制的NiFe/HfO_2/Si器件在低溫(10K)下的阻值很大,超過2 MW,比NiFe/Al_2O_3/Si器件大了2~3個(gè)數(shù)量級(jí);經(jīng)過退火以后,NiFe/HfO_2/Si器件的阻值降到了0.2 MW,有利于Hanle曲線測試;退火后的NiFe/HfO_2/Si器件測到了Hanle曲線,提取出了自旋壽命(256ps)和自旋擴(kuò)散長度(264 nm),并計(jì)算出了注入到Si中的自旋極化率,約為0.85%;2.NiFe/Al_2O_3/Si器件在退火前后都測到了Hanle曲線,并且自旋壽命和自旋擴(kuò)散長度都比NiFe/HfO_2/Si器件的略大,但是自旋極化率比較低,退火前僅為0.11%,退火后提高到了0.48%。(四)肖特基源、漏Ge pMOSFET的研制1.以低摻雜濃度的n型Ge為襯底,HfO_2為柵極介質(zhì)層,并以NiGe合金作為源、漏,制備了肖特基源、漏Ge pMOSFET;2.為了得到性能較好的Ge pMOSFET,對(duì)溝道Ge進(jìn)行了Si鈍化處理,并對(duì)有、無Si鈍化層的器件都進(jìn)行了電學(xué)特性測試,重點(diǎn)研究了樣品的轉(zhuǎn)移、輸出特性,并探討了Ge pMOSFET器件產(chǎn)生雙極性的原因。
[Abstract]:The development of silicon based spintronic devices is one of the research hotspot in the field of semiconductor spintronics applications. This paper focuses on the development of silicon spin injection three terminal device as the main line, focus on the NiFe/HfO_2/Si magnetic tunnel junction and the study of the interfacial properties of prepared silicon to develop new spin electronic devices. In addition, some of the exploration of Ge pMOSFET fabrication and electrical properties, accumulate experience for the future development of the spin transistor. (a) magnetic electrode NiFe thin film preparation and characterization of 1. high doped n type Si substrate, NiFe thin films with different thickness were prepared by magnetron sputtering, and some samples were annealed the system, study the relationship between the magnetic anisotropy and the thin films of the in-plane and out of plane thickness, and the influence of different annealing conditions on the magnetic properties, results show that in order to comply with the silicon based on magnetic spin injection Electrode film, NiFe film thickness should be controlled within 30 nm, and the annealing temperature to 250 DEG C is preferred; 2. in order to suppress the NiFe film Ni, Fe to Si substrate diffusion, but also in order to form a tunnel junction, between NiFe and Si into 2 nm thick HfO_2 thin film, and the annealing treatment on the magnetic properties of the samples before and after annealing, and the use of XPS test and analysis of the NiFe thin film components, chemical bonding and diffusion, results show that the introduction of HfO_2 layer can inhibit Ni, Fe to Si diffusion, makes Al (22 nm) /NiFe (28 nm /HfO_2 (2) nm) /Si samples were annealed at 250 C after the saturation magnetization is improved by about 80% to 3. of silicon spin injection; preparation of CoFe films is explored. (two) the dielectric layer of HfO_2 thin films preparation and electrical properties of the interface, respectively, 1. (E-beam) and atomic layer deposition (ALD) in high technology N doped Si substrate were prepared on HfO_2 thin films (thickness range of 0-5 nm), and analyze the use of XPS, Si on the growth of HfO_2 thin films were systematically studied, chemical bonding and diffusion, results show that the smaller HfO_2 ALD films grown by about 0.10 nm, roughness, thickness control precision high surface layer with chemical composition, may be suitable for silicon based on spin injection; 2. different preparation methods of Metal/HfO_2/n+-Si contact with the HfO_2 layer (E-beam0-5nm or ALD 0-2.5 nm) I-V characteristic variation, scheme for preparation of silica based spin injection into the tunneling layer of HfO_2 film was optimized; 3. NiFe/HfO_2 (0-2 nm I-V) characteristics of /p-Si contact, discusses the HfO_2 intercalation of NiFe/Si Schottky barrier height modulation effects and mechanism of spin injection pathfinder for future to low doping concentration of Si. (three) three terminal devices based on silicon spin injection Development and performance test and analysis of 1. of the first two chapters according to the research results of design process, prepared by the NiFe/HfO_2/n+-Si magnetic tunnel junction silicon as the core of the spin injection of three terminal device, for comparison with the parameters of the same NiFe/Al_2O_3/n+-Si three terminal devices were prepared, and some of the devices were annealed. The electrical properties of the device test (I-V characteristics) and spin injection characteristics (Hanle curve); results show that the developed NiFe/HfO_2/Si devices at low temperature (10K) of the resistance value is very large, more than 2 MW, ratio of NiFe/Al_2O_3/Si devices for 2~ 3 orders of magnitude; after annealing, the resistance of NiFe/HfO_2/Si devices down to 0.2 MW. To test Hanle curve; NiFe/HfO_2/Si device after annealing are measured by Hanle curve, extract the spin lifetime (256ps) and spin diffusion length (264 nm), and calculated the injection into the spin polarization in Si rate, About 0.85%; 2.NiFe/Al_2O_3/Si device before and after annealing are measured by Hanle curve, and the spin lifetime and spin diffusion length than the NiFe/HfO_2/Si device is slightly larger, but the spin polarization rate is relatively low, only 0.11% before annealing, annealing is improved to 0.48%. (four) Schottky source, drain Ge pMOSFET 1. to develop n type Ge low doping concentration as substrate, HfO_2 as the gate dielectric layer, taking NiGe alloy as the source, drain, Schottky source prepared drain Ge pMOSFET; 2. Ge pMOSFET in order to get better performance of channel Ge of Si passivation, and the device, without the passivation layer are Si the electrical testing, focus on the sample transfer, output characteristics, and discusses the reasons of producing bipolar pMOSFET devices Ge.

【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TN386

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