การตรวจสอบโครงสร้างจุลภาคของซิลิกอนเจอเมเนียมสำหรับทรานซิสเตอร์แบบจุดและแกเลียมไนไตรด์สำหรับไดโอดเลเซอร์โดยใช้เทคนิคจุลทรรศน์อิเล็กตรอนแบบส่องผ่าน / ภัทรจิตร มั่นทรัพย์ = Microstructural investigation of SiGe quantum dot transistors and GaN laser diodes using transmission electron microscopy
In this project, the effect of annealing temperatures on SiGe quantum dot transistors were studied. Si[subscript 0.9]Ge[subscript 0.1]were annealed at 800, 900 and 1300°c for 1 hour in hydrogen and nitrogen atmosphere. To study misfit dislocations, OM and TEM were used. TEM samples were prepared by flat surface grinding technique. From the result, there is no defect present because Ge composition is only 10%. At this composition, the epilayer is strained. The microstructures of W/Zr/nGaN ohmic contact annealed at 550, 650 and 850°c for 1 minute were studied using XRD, TEM and EDS. TEM samples were prepared by wedge technique. XRD patterns show the indication of several intermetallic phases presented at the contact layer. Results obtained from TEM and EDS confirmed the presence of these intermetallic phases. For the samples annealed at 550°c, WN₂, Ga₂Zr₃ and Ga₅W₂ were found. For the samples annealed at 650°c, Ga₃Zr₅, ZrN and Ga₂Zr₃ were found. For the sample annealed at 850°c, W₃N₄, Ga₃Zr₅ and Ga₂Zr₃ were found. Futhermore, The microstructure of W/V/nGaN ohmic contact annealed at 550 and 650°c for 1 minute were studied. The sample annealed at 550°c has a better contact resistivity than the sample annealed at 650°c. From the XRD results, Ga₅W₂, V₁₆N[subscript 1.5], Ga₅V₆, VN[subscript .81], Ga₇V₆, V₂Ga₅, Ga₄₁V₈, VN and VN[subscript 0.2] were found for the sample annealed at 550°c. For the sample annealed at 650°c, Ga₅V₆ and VN[subscript 0.81] were found. TEM and EDS results confirmed the intermetallic phases. The differences intermetallic phases formed at different annealing temperature have shown to influence the contact behavior.