【作者】 高丽丽；

【导师】 姚斌；

【作者基本信息】 吉林大学 ， 凝聚态物理， 2011， 博士

【摘要】 纤锌矿结构的MgxZn（1-x）O具有与ZnO相似的结构和光学特性,并且其带隙在一定范围内连续可调,近年来被看作是ZnO基LED的合适垒层材料。目前,人们已经能够制备出达到光电子器件要求的n型MgZnO合金薄膜。然而,p型MgZnO制备的研究进展却十分缓慢。在所有掺杂元素中,N被看作是ZnO或MgZnO比较适宜的p型掺杂元素。近十几年来,人们利用各种N源、掺杂方法和生长技术开展了N掺杂p型MgznO的研究工作,并取得了一定的成绩。但,仍存在着电阻率高、空穴载流子浓度低、迁移率低、稳定性差等问题。这主要是因为N的p型掺杂效率很低,通常N源在掺杂时会形成No受主,同时也会形成（N₂）0施主,对N受主进行自补偿,使电学性能下降,另一方面使薄膜晶体质量变差。可见,减少N₂,增加激活N原子的掺杂,即提高N的有效p型掺杂,对提高p型MgZnO的电学性能至关重要。然而N的含量和化学状态在样品中很难表征,另外Mg的加入是否能提高N的掺杂浓度也一直是人们关心的问题。本论文针对目前MgZnO研究中的热点,展开了一系列工作,取得的成果如下：（1）采用磁控溅射技术,选用高纯的N₂和Ar作为溅射气体,通过改变氮流量比调节生长条件,在石英衬底上制备N掺杂p型ZnO薄膜。通过对薄膜性能的研究表明,随着氮流量比的增加,薄膜中No与（N₂）o的掺杂浓度在变大。当氮流量比为20%时,得到电学性质最好的N掺杂p型ZnO薄膜,电阻率为20.54f2cm,迁移率为5.69cm²v^-1s^-1,空穴载流子浓度为5.49×10¹⁶ cm^-3。同时我们发现,随着薄膜中N含量的增加,吸收边在红移。（2）利用射频磁控溅射技术,用高纯的N₂和Ar作为溅射气体,通过改变氮流量比改变薄膜的生长条件,结果在氮流量比为20%时,经600℃真空退火30分钟,在石英衬底上制备出电阻率为21.47Ωcm,hall迁移率为3.45 cm2/Vs,载流子浓度为8.38×1016cm^-3p型Mg0.07Zn0.93O薄膜。在n型Si上沉积一层该薄膜制成异质结,异质结的Ⅰ-Ⅴ特性曲线表明该异质结具有良好的p-n结整流特性。通过研究退火温度对氮流量比为20%条件下的N₂/Ar混合气氛溅射制备的N掺杂MgZnO薄膜性能的影响,发现随着退火温度的升高,晶体质量不断提高；薄膜的导电性从n型变p型,最后又转变成弱p型,在中间退火温度600℃时,表现最好的p型导电性质。（3）采用磁控溅射技术,以高纯的N₂和Ar为溅射气体,分别用ZnO、Mg0.04Zn0.96O、Mg0.08Zn0.92O陶瓷靶,在石英衬底上生长N掺杂MgxZn（1-x）O薄膜。通过对薄膜性能的研究发现：在N掺杂的过程中,Mg的合金化对N的掺杂浓度和状态有一定的影响。随着Mg含量的增加,No的固溶度在降低,在N和O的化学势相同的条件下,Mg含量对No的固溶度起决定作用。同时,在相同的制备过程中,在N和O的化学势相同的条件下,Mg含量可以影响N的化学状态,在低Mg含量时,薄膜中可能会有No与（N₂）o同时存在,在高Mg含量时,薄膜中只存在（N₂）o一种形式。（4）研究了N掺杂ZnO和N掺杂MgxZn（1-x）O的Raman光谱,发现除ZnO的Raman振动模外有位于272、642cm-1的振动峰出现,并且随着氮流量比的增加,这两个峰以及位于580cm-1的振动峰峰强会增强。在相同氮流量比的条件下制备不同Mg含量的MgxZn（1-x）O:N薄膜,当Mg含量增加时,Raman光谱中位于272、642、580cm-1的振动峰峰强会减弱,同时XPS测试表明：No的含量在减少。通过对Raman和XPS的测试结果分析,可以推断位于272cm-1左右的这些新的振动模式只与No有关,与（N₂）0无关。更多还原

【Abstract】 Since the structure and optoelectronic properties of MgxZn（1-x）O alloy with wurtzite structure are very similar to ZnO and the band gap of MgxZn（1-x）O can be tuned, Mg-Zn-O alloy was proposed as a ZnO barrier layer. Now, n-type MgZnO with high crystal quality can readily be prepared, but fabrication of p-type MgZnO with good stability and electrical properties is still a difficult task. Some research groups have made many efforts to prepare p-type MgZnO by using N as acceptor dopant. However, it is hard to fabricate reproducibly N-doped p-type MgZnO with low resistivity, high carrier concentration and high mobility, due to low solubility of N in MgZnO and self-compensation of （N₂）o and other native donors for No acceptors. Obviously, it is very important to increase the solubility of No and decrease the self-compensation of （N₂）o for obtaining N-doped p-type MgZnO. Therefore, it is interesting to characterize chemical state and solubility of N in N-doped MgZnO correctly and simply and understand effect of Mg on the chemical state and solubility. In this thesis, a detailed investigation according to the present research difficulties on MgZnO has been carried out, and the following results are obtained:（1） N doped ZnO films were prepared on quartz substrates by r.f. magnetron sputtering method using ZnO target, with mixture of nitrogen and argon as sputtering gas. The effects of change of the flux ratio of N₂/（N₂+Ar） of sputtering gases on structure and properties of ZnO alloy thin films were investigated. when the flux ratio of N₂/（N₂+Ar） is 20%,the film of best p-type conductivity property has resistivity of 20.54Ωcm, Hall mobility of 5.69cm2/Vs and carrier concentration of 5.49x 1016 cm^-3. With the flux ratio of N₂/（N₂+Ar） increasing, the band-gap width occurs red shift.（2） N doped MgZnO films were prepared on quartz substrates using Mgo.04Zno.96O target, with mixture of nitrogen and argon as sputtering gas. The film of best p-type conductivity property has resistivity of 21.47 Qcm, Hall mobility of 3.45cm2/Vs and carrier concentration of 8.38×1016cm^-3, when the nitrogen partial pressure ratio is 20%. The p-type behavior of the film was confirmed by p-MgZnO/n-Si heterojunction which showed a clear p-n diode characteristic.The effects of annealing temperature on the structure and properties of MgZnO:N films were studied. We found that with the increasing annealing temperature, the crystallinity is improved, 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 600℃, the N doped MgZnO film behaves the best p-type conductivity property.（3） N doped MgxZn（1-x）O films were prepared on quartz substrates using ZnO, Mg0.04Zn0.96O and Mgo.08Zno.92O targets, respectively, with mixture of nitrogen and argon as sputtering gas. The solubility and chemical state of N in these films were studied. The solubility of No decreases with increasing Mg concentration. The chemical state of N in the MgZnO:N films is affected by Mg concentration.It can be changed from coexistence of No and （N₂）o in the MgZnO:N with low Mg concentration to only （N₂）o in the MgZnO:N with high Mg concentration.（4） The Raman spectra of ZnO:N and MgZnO:N were studied. The additional Raman peaks are observed at about 272 and 642 cm-1 in the ZnO:N films Raman spectra and the intensity of the additional peaks and 580 cm-1 peak increases with increasing the flux ratio of N₂/（N₂+Ar）. Raman spectra of the N-doped ZnO and MgxZn（1-x）O produced by the mixed gas with a fixed flux ratio indicate that the intensity of 272,642 and 580 cm-1 peaks decreases with increasing Mg concentration,and the XPS spectra of Nls of these films indicate No solubility decreases with increasing Mg concentration. So,the characteristic Raman peaks related to N doping observed in the N-doped ZnO and MgxZn（1-x）O at 272,642 and 580 cm-1, respectively, are demonstrated to be only related to No but not to更多还原