【作者】 隋瑛锐；

【导师】 姚斌；

【作者基本信息】 吉林大学 ， 凝聚态物理， 2010， 博士

【摘要】 本论文包括两大部分内容:第一部分针对氧化锌（ZnO）研究中存在的“p型ZnO的制备和性能”关键问题开展研究工作。目前,p型ZnO的制备仍然存在着高电阻率,低迁移率、低载流子浓度、性能不稳定等问题,本部分论文利用共掺杂提高受主杂质在ZnO中的固溶度和降低受主杂质离化能的方法制备p型ZnO。采用磁控溅射技术,以高纯的N₂和O₂为溅射气体,ZnO:BN（1at%）为靶材,在石英衬底上生长出B-N共掺ZnO薄膜。对其进行后热处理发现,随温度升高,薄膜的导电性从n型变成p型,最后又转变成弱p型,在中间退火温度650°C时,表现最好的p型导电性质,电阻率、载流子浓度、迁移率分别为2.3Ωcm,1.2×10¹⁷,11 cm²/Vs,与相同实验条件下制备的电阻率、载流子浓度、迁移率分别为50Ωcm,3.6×10¹⁶,4.4 cm²/Vs的N掺杂p型ZnO相比,p型导电性能得到提高。采用磁控溅射技术,讨论了在Ar和O₂溅射气氛下,氧流量比对B-N共掺ZnO薄膜电学性质的影响,测量结果表明,当氧流量比为70%时,在石英衬底上制备的B-N共掺杂ZnO薄膜具有最好的p型导电性质;研究了退火气氛对Ar/O₂溅射气氛下制备的B-N共掺ZnO薄膜性能的影响。研究结果发现,样品无论在真空还是氧气气氛下退火后都表现p型导电,但在真空气氛下退火后的p型导电性质要比在氧气气氛下退火后的p型导电性质好很多。真空气氛下退火样品的p型导电主要来自于No受主的贡献,而在氧气气氛下退火样品的p型导电主要来自于锌空位（VZn）受主的贡献。采用磁控溅射技术,利用高纯的Ar和N₂混合气体溅射ZnO:P₂O₅ （2wt%）靶,在石英衬底上生长出P-N共掺ZnO薄膜;经800℃真空退火,在富锌条件下,获得电阻率,载流子浓度和迁移率分别为3.98Ωcm,2.18×10¹⁸cm^-3,1.35 cm²/Vs的P-N共掺的p型ZnO薄膜,与相同实验条件下制备的P单掺和N单掺的p型ZnO薄膜相比,p型导电性能得到提高。通过实验结果分析,我们推断在P-N共掺p型ZnO价带边上形成一个由中性钝化（PZn-3No）复合体形成的完全被占据的杂质带,导致带隙宽度变小,该复合体和额外的作为No受主的N原子能够形成一种稳定结构的P_Zn-4N_o复合体,p型导电主要来自于这个P_Zn-4N_o复合体受主的贡献。验证了理论计算的正确性。第二部分针对Th3P4和尖晶石结构金属氮化物新型超硬材料的制备和性能开展研究工作。富氮的Zr-N化合物在常温常压下通常都是热力学亚稳相,并且合成困难,但对其研究无论是在理论上还是实验上都有重要意义。理论计算表明Th3P4结构的Zr₃N₄（c-Zr₃N₄）薄膜是一种新型超硬半导体材料,在机械、电子、光学等领域具有重要的应用,研究出制备c-Zr₃N₄薄膜的新的方法和技术是必要的。本部分论文利用磁控溅射技术在常压下制备富氮的Zr-N薄膜。采用磁控溅射技术,利用高纯的Ar和N₂为溅射气体,金属Zr为溅射靶材,衬底温度为500℃,在Si衬底上制备了由岩盐结构的ZrN（γ-ZrN）相和c-Zr₃N₄相组成的富氮的Zr-N薄膜;研究了N₂/（N₂+Ar）流量比（RN₂）对Zr-N薄膜的结构、性能的影响。研究结果表明,随着RN₂的增加,γ-ZrN相的相对含量不断减少,c-Zr₃N₄相的相对含量不断增加,Zr-N薄膜经历从γ-ZrN相到c-Zr₃N₄相的转变,经历着从导体向半导体的转变。在纯氮气的溅射下,衬底温度为100℃,在玻璃衬底上,氮气气氛下400℃原位退火后制备了具有单一相c-Zr₃N₄的薄膜。首次在实验上证明c-Zr₃N₄是一种p型半导体,禁带宽度为2.8 eV。在常温常压下c-Zr₃N₄薄膜的合成主要是薄膜生长的非平衡过程和晶格失配及热失配所产生的张应力共同作用的结果。更多还原

【Abstract】 Zinc oxide （ZnO） is a II-VI semiconductor with a wide band-gap of 3.37 eV and a hexagonal wurtzite structure. Due to its large exciton binding energy （60 meV）, it can be considered as a prime candidate for ultraviolet light emitting diodes and laser. The growth temperature of ZnO is only a half value of that of GaN, which reduces the atomic diffusion between the film and substrate. This makes it a promising candidate used in many areas, such as ultraviolet laser diodes, light emitting diode. Interest of ZnO a promising material for optoelectronic devices has intensified since the first reported in 1997 on the room-temperature ultraviolet （UV） laser emission of ZnO poly-crystallite thin films. Specifically, in the recent few years, more and more attentions have been attracted on electroluminescence.Recently many groups have reported successfully fabricating p-type ZnO. But, the fabrication of p-type ZnO exists normally the problem of high resistivity, low carrier concentration, low mobility, low doping concentration, and unstable, etc. There is a still long way to go to make p-type ZnO practicality. The key to obtain the high quality device is producible low resistivity and stable p-type ZnO.Aiming at the hot issues in current ZnO study field, in this section thesis, we focus on the the fabrication, structure, optical and electrical properties on B-N codoped and P-N codoped p-type ZnO. The major work and results are list as follow: （1） B-N codoped ZnO films were prepared on quartz substrates by r.f. magnetron sputtering method using ZnO:BN（1at%） target, using mixture of nitrogen and oxygen as sputtering gas. The effect of annealing temperature on the structure and properties of B-N codoped films was studied. Through the analysis of the experiment results, we draw this conclusion: with the increasing annealing temperature, the crystallinity is improved, the band-gap width first occur red shift and then blue shift, the conductivity of the film changed dramatically from n-type to p-type, and finally changed to weak p-type, at an intermediate annealing temperature 650°C, the B-N codoped ZnO film behaves the best p-type conductivity property, it has room-temperature resistivity of 2.3Ωcm, Hall mobility of 11 cm2/Vs and carrier concentration of 1.2×1017 cm-3, the p-type conduction comes from contribution of VZn and No acceptors. The p-type characteristics of the B-N codoped ZnO were improved remarkably as compared with N-doped ZnO fabricated under the same experiment condition. A ZnO homojunction was prepared by depositing a n-type ZnO layer on the B-N codoped p-type ZnO film and showed a rectification behavior.（2） Using magnetron sputtering technique, in argon and oxygen sputtering ambient, we discussed that the effect of oxygen partial pressure ratios on electrical properties of B-N codoped films. The hall measurement result indicate that when oxygen partial pressure ratio was 70%, the codoped ZnO film fabricated in quartz substrate at vacuum 600°C showed the best p-type conduction properties, which showed a restivity of 2.3Ωcm with a Hall mobility of 15 cm²/Vs and carrier concentration of 1.8×10¹⁷ cm^-3. The p-type behavior of B-N codoped ZnO films deposited in 70% of oxygen partial pressure ratio was confirmed by p-ZnO/n-Si heterojunction which showed a clear p-n diode characteristic. Meanwhile, the effect of post-annealing atmosphere on the properties of B-N codoped ZnO films fabricated in argon and oxygen sputtering ambient are studied. The results indicate that the hole concentration of the sample annealed in vacuum is about two order magnitudes higher than that of the sample annealed in oxygen. The p-conduction is attributed to No acceptors contribution for the B-N codoped p-ZnO obtained in vacuum and to VZn acceptor contribution for the B-N codoped p-ZnO obtained in oxygen ambient. （3） Using magnetron sputtering technique, in argon and nitrogen sputtering ambient, P₂O₅ and N₂ are served as dopant sources, the P-N codoped ZnO film fabricated in quartz substrate annealed 30 min at vacuum 800°C showed the best p-type conduction properties, which showed a restivity of 3.98Ωcm with a Hall mobility of 3.35 cm²/Vs and carrier concentration of 1.16×10¹⁸ cm^-3. The results analysis indicate that the p-type ZnO film was fabricated under Zn-rich condition, P substitute the site of Zn, N substitute the site of O in ZnO lattice to be an effective No acceptor. According to theoretical calculations in combine with the analysis of optical properties, we conclude that a passive stoichiometric （PZn–3No） complex was formed, which forms an additional fully occupied impurity band above VBM of pure ZnO, leading to the acceptor level decreasing due to the the valence band edge upward shift. The complex and an additional N atoms form a stable structure of P_Zn-4N_o complex, and the p-conduction is attributed to the P_Zn-4N_o complex acceptors contribution for the P-N codoped p-ZnO film.Transition metal nitrides,such as Zirconium nitride （Zr-N）, Titanium nitride （Ti-N）, etc., have been attracting much attention for various applications due to high intensity, great hardness as well as good thermal and conductive property. Many experimental results demonstrate that Zr-N compounds, produced in thermodynamic equilibrium state under atmospheric pressure, are usually poor nitrogen, and the highest N to Zr ratio is 1:1. However, preparation of N-rich Zr-N is proven difficult, and the N-rich Zr-N usually is metastable. Although it is generally difficult to fabricate N-rich Zr-N, investigation on N-rich Zr-N is interesting in theory and application. C-Zr₃N₄ film is a new and important material, but it is difficult to prepare the film. It is essential to search new method and techniques to fabricate the c-Zr₃N₄ film for its investigation in theory and application. In addition, although it is predicted in theory that the c-Zr₃N₄ is semiconductor, it is not demonstrated in experiment so far. Many studies have been performed in order to establish a relationship between the processing parameters, the film structure and properties. It is of special interest to explore the effect of processing parameters on structure and properties of N-rich nitrides. In this section thesis, we focus on the the fabrication, characterization of the structure, optical and electrical properties on N-rich Zr-N film. The major work and results are list as follow:（1） N-rich Zr-N thin film composed of c-Zr₃N₄ andγ-ZrN was deposited on Si substrates at 500°C using radio frequency （rf） magnetron sputtering technique by sputtering Zr target, using argen and nitrogen as sputtering gas, and a single phase of c-Zr₃N₄ film was grown on a glass substrate at 100°C and then annealing at 400°C under the N₂ ambient. Hall measurement indicates that the c-Zr₃N₄ compound is a p-type semiconductor with resistivity of 2.121×10⁴Ωcm, carrier concentration of 9×10¹⁴ cm^-3 and Hall mobility of 0.34 cm2/Vs. Its bandgap was evaluated to be about 2.8 eV. Formation of the c-Zr₃N₄ film is suggested to be attributed to non-equilibrium process of film growth and the action of the tensile stress induced by lattice and thermal mismatches.（2） Effects of N₂ : （N₂+Ar） flow ratio on the structure and properties of the films are systematically studied. Studies result indicate that for the Zr-N flim grown on glass at 400°C and RN₂≤20%, it consists mainly ofγ-ZrNx. The N concenttratin and lattice constant of theγ-ZrNx increase with increasing RN₂. For the Zr-N film grown on Si at 500°C and RN₂ ranging from 20 to 100%, it is composed ofγ-ZrN and c-Zr₃N₄ The relative content decrease forγ-ZrN but increases for c-Zr₃N₄ with increasing RN₂.The Zr-N film undergo from theγ-ZrN phase to c-Zr₃N₄ phase, and undergo from the conductor to the semiconductor.更多还原