GaN和GaN:Mg外延膜低温拉曼谱的对比研究

对液氮温度下六方相GaN和掺Mg的P型GaN薄膜的拉曼谱进行了对比研究。除对两个样品中主晶格振动模进行了对比分析外,着重讨论了位于247 cm-1的散射峰的产生机制。结果表明GaN:Mg的谱中该峰的散射强度随温度升高先增大再减小,在500K以上消失且对样品重新降温到78K观察此峰不再出现,因此认为它是缺陷产生的振动模。而GaN样品中经同样加热降温的过程此峰仍然存在,说明两个样品中该峰的产生机制不同。此外,在GaN:Mg的谱中还观察到Mg诱导的局域振动模。

Comparative Analysis of Raman Spectra of GaN and GaN:Mg Epitaxial Layer at Low Temperature

Raman spectra of GaN and Mg-doped GaN films have been investigated.The host phonon modes of Mg-doped GaN were compared with those of undoped GaN.The origin of the peak at 247cm~(-1) was discussed.In Mg-doped GaN sample the intensity of this peak became strong at first,but then became weak and disappeared at about 500K.When the temperature re-decreased to 78K this peak is absent.We attributed it to the defect-induced vibrational mode.But in undoped GaN the peak has different character,this implies the peak of GaN has different origin from which of GaN:Mg.The Mg-induced local vibrational modes have also been observed in the spectrum of GaN:Mg.