Zn和Mg掺杂氧化镓薄膜的制备与表征

发布时间：2018-05-16 22:09

  本文选题：β-Ga_2O_3薄膜 + 磁控溅射　； 参考：《浙江理工大学》2017年硕士论文

【摘要】：氧化镓(Ga_2O_3)是一种新型的宽禁带半导体材料,禁带宽度约为4.98 eV,有五种同分异构体(α、β、γ、ε、δ),其中最稳定的是β-Ga_2O_3。β-Ga_2O_3有许多良好的物理性能,如:禁带宽度大,击穿场强高,介电常数大,在可见光和紫外光波段透过率高,热稳定性和化学稳定性好,在未来的电子器件中具有重要的应用前景,如:日盲紫外光电探测器、场效应晶体管、透明导电电极等。与一般氧化物半导体类似,本征β-Ga_2O_3通常表现出n型导电,并由于氧空位等缺陷的自补偿效应,p型Ga_2O_3很难获得。但器件的应用又往往基于pn结。理论上,二价元素的掺杂将会实现Ga_2O_3薄膜的p型转变。本论文利用磁控溅射方法分别制备了Zn和Mg二价元素掺杂的Ga_2O_3薄膜,并采用X射线衍射,紫外-可见分光光度计,X射线光电子能谱分析仪等手段对掺杂前后薄膜的结构特性、表面形貌、光学性能、元素成分进行了分析。同时,我们还制备了基于本征Ga_2O_3薄膜和掺杂Ga_2O_3薄膜的金属-半导体-金属(MSM)结构的日盲紫外光电探测器元件,研究掺杂对Ga_2O_3薄膜日盲紫外探测器元件性能的影响。本文的主要研究内容与结论如下:(1)本文采用磁控溅射法研究了β-Ga_2O_3薄膜的生长条件,主要研究了衬底温度和沉积压强对薄膜质量和结晶性能的影响,获得了β-Ga_2O_3薄膜的最佳生长条件为衬底温度750℃,沉积气压0.8 Pa。(2)采用磁控溅射法制备了Zn掺杂Ga_2O_3薄膜,通过在Ga_2O_3靶材上放置不同颗粒的ZnO小片获得不同Zn掺杂浓度的Ga_2O_3薄膜,对掺杂薄膜的结构特性,元素成分,光学性能和电学性能进行了表征。掺杂后得到的薄膜仍是单斜晶系的β-Ga_2O_3薄膜,由于Zn2+半径大于Ga3+,掺杂后薄膜的XRD衍射峰向小角度偏移。随着Zn掺杂浓度的增加,薄膜的禁带宽度变小,这是由于掺杂引入了杂质能级。掺杂薄膜日盲紫外光电探测器元件在365 nm紫外光激发下没有响应,在254 nm紫外光激发下最大的光暗比达到110,而本征Ga_2O_3薄膜在254 nm紫外光激发下的光暗比最高为30,而且由于Zn的掺杂减少了薄膜中氧空位浓度,相比于本征Ga_2O_3薄膜,掺杂后的薄膜具有更快的响应时间。采用磁控溅射法制备了Mg掺杂Ga_2O_3薄膜,研究了Mg掺杂对Ga_2O_3薄膜结构,性能的影响。由于Mg2+的半径大于Ga3+,所以掺杂后薄膜衍射峰向小角度偏移。制备了基于Mg掺杂Ga_2O_3薄膜的金属-半导体-金属(MSM)结构的日盲紫外光电探测器元件,相比于本征氧化镓薄膜,具有更快的响应时间。并且在不同偏压下该器件具有良好的可重复性和高的稳定性。(3)我们对Zn和Mg掺杂薄膜进行了不同温度的退火处理,随着退火温度的增加,供给原子吸收的能量越来越高,使得晶粒在择优取向时有足够的能量进行重排,所以掺杂薄膜的结晶性越来越好。当退火温度为900℃时,Mg掺杂氧化镓薄膜晶粒的择优生长发生变化。且随着退火温度的升高,掺杂薄膜的光学带隙变大。
[Abstract]:Ga2O3 is a new type of wide band gap semiconductor material, with a band gap of about 4.98 EV and five isomers (伪, 尾, 纬, 蔚, 未), of which the most stable is the 尾 -Ga2O3.The 尾 -Ga2O2O3 has many good physical properties, such as: wide bandgap, high breakdown field strength, large dielectric constant, It has high transmittance, thermal stability and chemical stability in visible and ultraviolet bands, and has important application prospects in the future electronic devices, such as solar blind ultraviolet photodetectors, field effect transistors, transparent conductive electrodes, etc. Similar to general oxide semiconductors, intrinsic 尾 -Ga2O3 usually exhibits n-type conduction, and it is difficult to obtain p-type Ga_2O_3 due to self-compensation effect of defects such as oxygen vacancies. However, the applications of devices are often based on PN junctions. Theoretically, the doping of bivalent elements will realize the p-type transition of Ga_2O_3 thin films. In this paper, Zn and mg doped Ga_2O_3 thin films were prepared by magnetron sputtering, and the structure characteristics of the films before and after doping were investigated by means of X-ray diffraction, UV-Vis spectrophotometer and X-ray photoelectron spectroscopy (XPS). Surface morphology, optical properties and elemental composition were analyzed. At the same time, we have fabricated solar blind UV photodetectors based on intrinsic Ga_2O_3 thin films and metal-semiconductor-metal Ga_2O_3 doped Ga_2O_3 thin films. The effect of doping on the performance of Ga_2O_3 thin film solar blind UV detectors is studied. The main contents and conclusions of this paper are as follows: (1) in this paper, the growth conditions of 尾 -Ga2O3 thin films are studied by magnetron sputtering, and the effects of substrate temperature and deposition pressure on the quality and crystallization properties of the films are studied. The optimum growth conditions of 尾 -Ga2O3 thin films were obtained as follows: substrate temperature 750 鈩，

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