基于AlN和GaN形核层的AlGaN/GaN HEMT外延材料和器件对比

使用金属有机物化学气相淀积(MOCVD)方法在蓝宝石衬底上分别采用AlN和GaN作为形核层生长了AlGaN/GaN高电子迁移率晶体管(HEMT)外延材料,并进行了器件制备和性能分析.通过原子力显微镜(AFM)、高分辨率X射线双晶衍射仪(HR-XRD)和二次离子质谱仪(SIMS)等仪器对两种样品进行了对比分析,结果表明采用AlN形核层的GaN外延材料具有更低的位错密度,且缓冲层中氧元素的拖尾现象得到有效地抑制.器件直流特性显示,与基于GaN形核层的器件相比,基于AlN形核层的器件泄漏电流低3个数量级.脉冲Ⅰ-Ⅴ测试发现基于GaN形核层的HEMT器件受缓冲层陷阱影响较大,而基于AlN形核层的HEMT器件缓冲层陷阱作用不明显.

Comparison of AlGaN/GaN HEMT Epitaxial Materials and Devices Between AlN and GaN Nucleation Layers

AlGaN/GaN high electron mobility transistor (HEMT) epitaxial materials were grown on sapphire substrate with AlN and GaN nucleation layers by metal organic chemical vapor deposition (MOCVD) method,and the related devices were fabricated and the properties were analyzed.The samples were compared and analyzed by the atomic force microscope (AFM),high resolution X-ray double crystal diffractometer (HR-XRD) and secondary ion mass spectrometer (SIMS).The results show that the GaN epitaxial material with AlN nucleation layer has lower dislocation densities and oxygen tailing effect in buffer layer was suppressed.The DC characteristics of the devices show that the leakage current of devices based on AlN nucleation layer was three orders of magnitude lower than that of the device with GaN nucleation layer.The results of pulse Ⅰ-Ⅴ test show that traps in buffer layer have a greater impact on the devices with GaN nucleation layer than those with AlN nucleation layer.