摘要
在低压金属有机化学气相沉积(LP-MOCVD)系统中利用侧向外延生长(epitaxial lateral overgrowth,ELO)技术进行了二次外延GaN的研究。SEM观察结果表明,翼区和窗口区宽度比值不同的图形衬底,侧向和纵向的生长速率不同;其AFM表面形貌图像表明,长平的ELO-GaN表面平整,位错密度较低。ELO-GaN的光致发光(PL)谱的带边峰比传统方法生长的GaN的带边峰红移了14.0 meV,表明ELO-GaN的应力得到部分释放,晶体质量提高。ELO-GaN和普通外延GaN的拉曼散射谱比较表明,ELO-GaN中的应力较小,晶体质量较高,A1(TO)模的出现说明其晶轴取向相对于(0001)方向发生微小的偏移。
To improve the quality of the crystal,the epitaxial lateral overgrowth(ELO) technique is applied to the growth of GaN.ELO-GaN on patterned SiO2/GaN/α-Al2O3 substrate is grown by low pressure metalorganic chemical vapor deposition(LP-MOCVD).The results of a systematic study of the ELO-GaN are reported.The scanning electrical microscopy(SEM) Cross-sectional image of ELO-GaN with different growth time indicate the ratio of the lateral growth velocity to that of vertical decrease with increase the fill factor of the pattern substrate.Atomic force microscopy(AFM) images showed that the surface of ELO-GaN is smooth and the dislocation density is much lower than the conventional GaN.The room temperature photoluminescence(PL) of the ELO-GaN show that the near-band emission peak of ELO-GaN has a red shift of 14.0 meV comparing with that of the conventional grown GaN.This means that the stress in ELO GaN has been released partially.Raman scattering spectrum revealed that the stress in the ELO-GaN is smaller than that in the conventional grown GaN and also the quality of ELO-GaN is much higher.But the appearanceof the A1(TO) model in the ELO-GaN revealed the tilts in the <1120> direction between GaN in window regions and mask regions.In a word,the quality of GaN crystalloid is effectively improved by MOCVD using the ELO technique.
出处
《微细加工技术》
2008年第6期48-52,共5页
Microfabrication Technology
基金
国家自然科学基金资助项目(60276029)
国家863计划资助项目(2004AA311020
2006AA032409)
福建省科技项目和基金资助项目(2006H0092
A0210006
2005HZ1018)
