用N_2-H_2等离子体氮化GaAs衬底对ECR-PEMOCVD生长立方GaN的影响(英文)

Effects of GaAs Substrate Nitridation with N_2-H_2 Plasma on c-GaN Epitaxy Growth by ECR-PEMOCVD

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( 0 0 1 )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 4 0 %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。

The effects of nit ridation conditions to GaAs (001) substrates in N 2 H 2 plasmas on c G aN film grown by electron cyclotron resonance plasma enhanced metalorganic c hemi cal vapor deposition (ECRPE MOCVD) was investigated. It was found that there ha ve 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 epit axy film grow ing with hydrogen plasma during nitridation was improved exceeds 40% compared wi th that of epitaxy film growing without hydrogen plasma during nitridation. Atom ic force microscopy (AFM) observation showed that the surface of buffer layers becomes smoother a nd the crystallites become larger when nitridated in N 2 H 2 plasmas. We thin k that the uniform nucleation of GaAs (001) substrate surface is a crucial facto r for getting better crystalline quality of c GaN. Finally, a chemical mode l is put forward to interpret the influence of hydrogen plasma during the ni tridation process.