氮化鎵薄膜奈米結構製作及特性研究

Abstract

在這篇論文中,我們成功的將氮化鎵薄膜奈米結構製作出來，並且研究其特性。我們將成長出來的三明治結構(GaN/ZnO/GaN)利用高選擇比的濕式化學蝕刻將氮化鎵薄膜奈米結構製作出來，其中，最關鍵的部分是選擇使用氧化鋅做為犧牲層。為了避免氧化鋅在高於650℃的溫度下會開始游離的特性，我們利用分子束磊晶系統在低溫下成長氧化鋅層，並且成功的利用分子束磊晶在氧化鋅層上再成長氮化鎵。成長完的樣品，我們分別利用XRD、SEM、AFM、CL以及PL去判斷再成長氮化鎵的品質。接著，利用濕式化學蝕刻的方式將底下的氧化鋅犧牲層掏空，由SEM的影像可以看到底下已經掏空乾淨的氮化鎵薄膜，並且對於蝕刻完成的氮化鎵薄膜層做一些光學特性的討論。最後，我們也成功的在氮化鎵薄膜上了光子晶體H2共振腔結構，使得氮化鎵薄膜在水平面上能有相當好的光學侷限，並且在垂直方向上藉由全反射提供良好的光學侷限，因此在模擬中，光子能隙能夠存在於我們所製作的結構中。

In this thesis, we have fabricated and investigated the GaN-based membrane nanostructure. The GaN membrane nanostructure is realized by high selective wet chemical etching of the sandwitched structure consisted of GaN/ZnO/GaN layer. The ZnO layer in the sandwitched structure plays an important role as a sacrificial layer. To prepare the sandwitched GaN/ZnO/GaN structure, we have used the MBE system to regrowth the GaN/ZnO layer on GaN templates in order to avoid the ZnO dissociation problem. We have also measured the XRD, SEM, AFM, CL and PL to check film quality of the regrowthed GaN layer. Next, the ZnO sacrificial layer would be removed by wet chemical etching. The SEM images showed the clearly GaN-based membrane nanostructure. The optical characteristics of GaN-based membrane nanostructure have also investigated by temperature dependent Photoluminecence (PL). Finally, the photnic crystal H2 defect cavity is realized on the GaN-based membrane nanostructure. Due to the great optical confinement by total internal reflection (TIR), the Photonic Bandgap (PBG) could be existed in the GaN-based H2 defect cavity by simulation.