用N2-H2等离子体氮化GaAs衬底对ECR-PEMOCVD生长立方GaN的影响

我们研究了采用电子回旋共振等离子体增强金属有机化学气相沉积(ECR-PEMOCVE)技术在GaAs(001)衬底上外延生长立方GaN的过程中衬底氮化条件对外延膜生长的影响.发现氮化时在氮等离子体中加入氢等离子体对于立方GaN薄膜生长具有显著影响.和氮化过程中不加入氢等离子体相比,氮化过程中加入氢等离子体生长出的外延膜其X射线衍射(XRD)半高宽(FWHM)可以最高降低40%以上.原子力显微镜(AFM)观察表明:在N2-H2混合等离子中氮化过的衬底上外延的缓冲层表面变得更为平滑,晶粒也变得粗大.最后,我们提出了一个化学模型对上述结果进行了分析和解释..

Effects of GaAs Substrate Nitridation with N2-H2 Plasma on c-GaN Epitaxy Growth by ECR-PEMOCVD

The effects of nitridation conditions to GaAs (001) substrates in N2-H2 plasmas on c-GaN film grown by electron-cyclotron-resonance plasma enhanced metalorganic chemical vapor deposition (ECRPE-MOCVD) was investigated. It was found that there have remarkable effects on the growth of c-GaN film when hydrogen plasma was added during nitridation. XRD ( θ - 2θ)analysis showed that the FWHM of epitaxy film growing with hydrogen plasma during nitridation was improved exceeds 40 % compared with that of epitaxy film growing without hydrogen plasma during nitridation. Atomic force microscopy (AFM) observation showed that the surface of buffer layers becomes smoother and the crystallites become larger when nitridated in N2-H2 plasmas. We think that the uniform nucleation of GaAs (001) substrate surface is a crucial factor for getting better crystalline quality of c-GaN. Finally, a chemical model is put forward to interpret the influence of hydrogen plasma during the nitridation process.