- 學位論文
準一維氮化鎵半導體p-n接面的電性及顯微研究
Nanoelectrical properties of quasi one-dimensional GaN p-n junction probed by electron microscopy
摘要
本實驗室目前可以成功的利用黃光微影製程製作單根奈米柱二極體元件，並利用場發射掃描式電子顯微鏡(FE-SEM)結合奈米操控系統做電性量測的優勢，我們可以量測到外加偏壓下p-n接面的影像變化，其呈現的影像與偵測器接收的二次散射電子濃度成正比的關係，藉此做影像分析，推論出空乏區寬度與p-n接面位障。另一方面，目前利用霍爾量測的方式，研究半導體塊材的載子濃度被廣泛地使用，但霍爾量測目前尚未發展出一套方式可測量一維奈米線載子濃度。有鑑於此，本論文的研究方向，提出一個方法，觀察並且量測p-n接面二極體在顯微系統下的特性變化，諸如利用FE-SEM影像(散射電子影像)直觀的觀察空乏區寬度隨逆向偏壓的影響、不同逆向偏壓電子空間位能分佈情形等等，經由關係式換算可得一維二極體的空間電場分布，藉此得到p型區與n型區域的載子濃度比例，並可加以推算半導體的p型或n型區域所攜的載子濃度。
並列摘要
One-dimensional Ⅲ-nitride (AlN, GaN, InN) nanorod structures are well known to have great prospects for fundamental studies and novel technological applications. However, direct determination of the carrier concentrations by Hall effect is not easy if not impossible for nanorod structures. Here, we demonstrate a method which can be applied to study single GaN nanorod p-n junctions grown by plasma-assisted molecular-beam epitaxy (PAMBE) with an in-situ multiple-probe system installed in a field-emission scanning electron microscope (FESEM). We can directly observe the electrostatic potential variation across the depletion region in the reversely biased nanorods, and the electrostatic potential can be determined directly from secondary electron images. In particular, we show that this method can be use for estimating the carrier concentration in single GaN nanorod p-n junctions.