衬底类型对于Ga-N共掺杂ZnMgO薄膜性能的影响

Effect of Substrate Style on Properties of Ga-N Codoped ZnMgO Thin Films

利用直流反应磁控溅射技术分别在玻璃、n-〈111〉Si、氧化硅(SiO2/Si)、石英衬底上制得Ga-N共掺杂ZnMgO薄膜。利用X射线衍射(XRD)、Hall实验、场发射扫描电镜(FE-SEM)和X射线光电子能谱(XPS)对不同衬底上生长的ZnMgO薄膜的性能进行表征。结果表明,Ga-N共掺杂p型ZnMgO薄膜具有高度c轴择优取向的结构特征。生长在玻璃、(111)Si和氧化硅衬底上的ZnMgO薄膜显示p型导电性,而生长在石英衬底上的ZnMgO薄膜显示n型导电性。生长在氧化硅片衬底上的共掺杂ZnMgO薄膜的晶体质量和电学性能最优,载流子浓度为2.28×1017cm-3,电阻率为27.7Ω·cm。而且其表面形貌明显不同于生长在其他衬底上的薄膜。Ga2p和N1s的XPS谱表明Ga-N共掺杂ZnMgO薄膜中存在Ga—N键,有利于N的掺入,从而易于实现p型生长。

By alloying MgO with ZnO, ZnMgO exhibits a wider bandgap than pure ZnO and has a similar lattice constant to that of ZnO. Therefore ZnMgO can be used as a potential barrier to enhance the quantum efficiency for ZnO/ZnMgO heterostructures, such as quantum wells, superlattices, laser diodes and so on. However, one major challenge is to achieve high quality and stable p-type ZnMgO. Recently, p-type ZnMgO have been investigated by doping with P, Sb, Li, and codoping of A1 and N by pulse laser deposition, rf magnetron sputtering, ultrasonic spray pyrolysis or dc magnetron sputtering. In this letter, p-type ZnMgO thin films were realized by Ga-N codoping method via dc reactive magnetron sputtering. ZnMgO thin films were deposited on glass, n-Si wafer, wet oxidated n-Si substrate （SiO2/n-Si） and quartz respectively. N2O was used as the source of N and O. Hall-effect measurements reveal that the optimal reliable p-type conduction is achieved on the wet oxidated n-Si substrate with a hole concentration of 2.28×10^17cm^-3, and a resistivity of 27.7Ω ·cm. XPS results suggest the presence of Ga-N bonds and thus validate the codoping method. According to the XRD patterns, p-type ZnMgO thin films exhibit good crystallinity with （002） orientation. The full width at half maximum （FWHM） of （002） diffraction peak are 0.61°, 0. 392° to 0. 314°,respectively, for the films deposited on glass, n-Si wafer, wet oxidated n-Si substrates. It is reasonable to consider that the crystallinity is improved evidently when the films deposited on SiO2/n-Si substrate. The FE-SEM image of the film deposited on SiO2/n-Si substrate is obviously different from that on the other substrates.