- 學位論文
由溝渠圖騰氮化鎵基版所成長的氮化鋁鎵六角V形孔洞之特性研究
Characteristics of hexagonal V pits in AlGaN films grown on patterned GaN templates
摘要
在此論文中，我們研究了以有溝渠圖騰氮化鎵基版所成長的氮化鋁鎵六角V形凹洞的特性。我們發現隨著溝渠深度的變化，可以控制V形凹洞的形成和氮化鋁鎵的光學特性。當溝渠的深度到達1.0 微米時，V形凹洞的形成將被抑制。而當溝渠的深度到達1.5 微米時,大量的V形凹洞將沿著溝渠方向產生。陰極射線的螢光光譜顯示了很強的能隙發光強度在V形凹洞的邊緣發生。穿遂式電子顯微術的影像解釋了空間中強度的變化是由於V形凹洞的邊緣具有較少的差排聚集。然而，橫切面的陰極射線螢光光譜和X射線色散分析顯示了在V形凹洞裡組成成分的不同。大量的鎵金屬在V形凹洞的頂端聚集並且提供了許多的非輻射中心以致於能隙發光強度的減弱。最後，結合掃瞄式電位顯微技術，V形凹洞的能帶結構第一次被建立。而我們認為這對瞭解V形凹洞的物理特性研究是非常有幫助的。
並列摘要
We reported an investigation of physical properties of AlGaN films grown on patterned GaN templates. It is found that with the patterned grooved-GaN templates, it is possible to manipulate the formation of the V-shape pits and optical property of AlGaN films. For a trench depth of 1.0 um, the V-shape pits can be greatly suppressed. While the GaN trench depth is up to 1.5 um, a large number of the V-shape pits present along the trench. Cathodoluminescence (CL) spectra show a strong band-edge emission around the V-shape pits. Transmission electron microscopy (TEM) data suggest that the spatial variation of intensity is due to the absence of dislocations in the sidewall of the V-shape pit. Cross-sectional CL spectrum and energy-dispersive X-ray (EDX) show compositional variation in the V-shape pits. The formation of Ga-rich domains exists in the invert apex of the V-shape pits, which induces a large density of non-radiative centers and reduces the emitted intensity. Finally, combining with the scanning Kelvin microscopy measurement, the energy band alignment of the V-shape pits is constructed for the first time, which is very useful for the understanding of physical properties of the V-shape pits.