TMIn流量对GaN基蓝光LED外延薄膜的影响

以蓝宝石(Al2O3)为衬底,采用有机金属化学气相沉积(MOCVD)技术生长InGaN/GaN多量子阱结构.本文通过调整外延生长过程中三甲基铟(TMIn)流量,研究了TMIn流量对InGaN/GaN多量子阱结构的合金组分、晶体质量和光学性质的影响.本文采用高分辨X射线衍射(HRXRD)、原子力显微镜(AFM)和光致发光(PL)测试表征其结构和光学性质.HRXRD测试结果表明,随TMIn流量增加,"0"级峰与GaN峰之间角偏离增大,更多的In并入薄膜中.HRXRD与AFM表征结果表明:增大TMIn流量会导致外延薄膜中的位错密度增大,V形坑数量增加,晶体质量严重恶化;PL测试结果表明,随着TMIn流量增加,发光强度逐渐降低,半高宽增大,这是由于晶体质量恶化所导致.因此严格控制铟源流量对于改善量子阱薄膜的晶体质量与光学性质有着至关重要的作用.

Effect of TMIn Flow on Epitaxial Film of GaN-Based Blue Light Emitting Diodes

InGaN/GaN MQWs were grown on sapphire(Al2O3) substrates by Metal-Organic Chemical Vapor Deposition(MOCVD).The influence of TMIn flow on the alloy content, crystal quality and optical properties of InGaN/GaN MQWs were investigated by adjusting the TMIn flow in epitaxial growth process.Structural and optical properties of MQWs were characterized by high-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM) and photoluminescence (PL).HRXRD shows that with the increase of TMIn flow, the angle between the "0" peak and the GaN peak deviates from each other, and more In is incorporated into the film.HRXRD and AFM shows that with the increasing of TMIn flow, the density of dislocation and V-pits increases, and the crystal quality severely deteriorate.It is also found that the weaker PL intensity and larger FWHM value are presented with increasing TMIn fiow, which could be attributed to the deterioration of the crystal quality confirmed by HRXRD and AFM results.Thus, the structual and optical properties of InGaN/GaN MQWs are strongly affected by the TMIn flow.