應用於紫外光二極體的氮化物二維電洞氣;Nitride-based two dimensional hole gas for UV LED applications

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/92302

Title:	應用於紫外光二極體的氮化物二維電洞氣;Nitride-based two dimensional hole gas for UV LED applications
Authors:	李孟泓;Hong, Li-Meng
Contributors:	光電科學與工程學系
Keywords:	二維電洞氣
Date:	2023-07-18
Issue Date:	2024-09-19 15:45:31 (UTC+8)
Publisher:	國立中央大學
Abstract:	深紫外發光二極體（波長≤290 nm）在目前的設計中通常選用P型結構來提高導電性。然而，P型結構中鎂離子的摻雜會形成中間能階(位於價電帶邊界上方約 150~220 meV )，此能階會吸收量子井中載子複合後所產生的紫外光，降低元件的發光效率。因此，我們致力於開發一種以未摻雜的GaN和高品質的AlN結構形成的二維電洞氣(2-dimensional hole gas, 2DHG)來實現高導電、高穿透的性能。利用二維電洞氣，我們能解決使用P型結構中摻雜鎂離子所引起的吸光問題。同時，由於二維電洞氣之磊晶層的厚度相對傳統P型結構更薄，更能減緩P型磊晶層的吸光問題，達成高紫外光穿透的目標。在本研究中，我們利用一維 drift-diffusion charge control solver (1D DDCC) 軟體進行能帶模擬。從模擬結果中觀察到，在15 nm的GaN磊晶覆蓋層厚度下，AlGaN量子井表面的電洞濃度可達最大值9.7×1020 cm-3。本研究使用有機金屬化學氣相沉積法成長GaN/AlN磊晶層，希望得到高品質的二維電洞氣。我們以兩吋c-plane藍寶石為基板，先成長一層AlN，再成長GaN。透過磊晶時間來調整GaN磊晶層的厚度，並分析不同厚度的GaN對於磊晶品質和元件電性的影響。未來，我們將持續優化二維電洞氣的磊晶條件，以提高磊晶品質，並將其應用於DUV LED結構，以提升發光效率。 ;Deep ultraviolet light-emitting diodes (DUV LEDs, wavelength ≤ 290 nm) typically utilize a p-type contact layer to control the current spreading and light extraction efficiency. However, doping with magnesium acceptors in the p-type layer creates impurity levels (150~220 meV above the valence band), which absorb the ultraviolet light generated by carrier recombination in the quantum well. Therefore, we are devoted to developing a two-dimensional hole gas (2DHG) formed by undoped GaN and high-quality AlN structures to achieve high conductivity and high transparency. Using the 2DHG, we can overcome the light absorption issues caused by impurity levels. Additionally, the thin (< 30 nm) epitaxial layer of 2DHG can minimize the UV absorption. In this study, we conducted simulations using a one-dimensional drift-diffusion charge control (DDCC) solver. From the simulation results, it was observed that the hole concentration reached a maximum value of 9.7×1020 cm-3 at the GaN capping layer thickness of 15 nm on the AlGaN quantum wells. To grow high-quality 2DHG, we employed metal-organic chemical vapor deposition (MOCVD) and 2-inch c-plane sapphire substrates. We aim to form the 2DHG by the interface of GaN/AlN. The epitaxial thickness of GaN was controlled by adjusting the growth time, and the effect of GaN layer thicknesses on epitaxial quality and device electrical properties was investigated.
Appears in Collections:	[Graduate Institute of Optics and Photonics] Electronic Thesis & Dissertation

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