GaN和GaN:Mg外延膜低温拉曼谱的对比研究

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

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。

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 CaN 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.