半極化面氮化銦鎵/氮化鎵全彩奈米金字塔發光二極體之製作及特性研究

Abstract

本篇論文中，我們介紹如何在極化面氮化鎵奈米柱基板上，使用選區成長技術成長高銦含量的半極性面{10-11}氮化銦鎵╱氮化鎵多量子阱結構。 我們使用電漿輔助化學氣相沉積(Plasma Enhance Vapor Chemical Deposition, PECVD)成長二氧化矽(Silicon Dioxide, SiO2)，並使用反應性離子蝕刻(Reactive Ion Etching, RIE)作選擇性蝕刻後得到具高均勻性側壁保護層(side wall passivation)作選擇性成長，並對樣品作空間解析陰極射線螢光(Cathodoluminescence, CL)影像作討論。另外變溫光激發螢光(Temperature Dependent Photoluminance, TDPL)隨著溫度變化量測中，從發光能量隨溫度的變化可以得到半極化面於成長時具較小的銦叢集以致等效載子侷限程度也較極化平面(0001)小，從擬合曲線得出從極化平面的22 meV下降至接近0 meV；而內部量子效率(Internal Quantum Efficiency, IQE)也較高，從22% 提升至30%；且使用時間解析光激發螢光(Time-Resolved Photoluminescence, TRPL)量測顯示半極化面多重子阱結構的輻射復合時間遠比極化面短，在低溫從85 ns 下降至 0.21 ns，歸因於量子侷限史塔克效應(Quantum Confine Stark Effect, QCSE)減緩，而在變溫時間解析光激發螢光(Temperature Dependent Time-Resolved Photoluminescence, TD-TRPL)計算得到半極化面綠光、黃綠光及琥珀色光於近室溫及室溫時仍具有二維激子 (2D exciton) 發光特性，也代表著屬於量子阱貢獻發光。隨後，我們使用時域有限差分法(Finite-Difference Time-Domain, FDTD)計算，計算得到具奈米結構之發光元件比傳統平面及具圖形化藍寶石基板的發光元件，提升了147%的光取出效率(Light Extraction Efficiency, LEE)。 最後，我們把半極化面及極化面的發光二極體完成，並使用電激發螢光(Electroluminescence, EL)量測分析出L-I-V曲線外，並作出半高寬(Full Width at Half Maximum, FWHM)及峰波長隨電流從664 nm藍移至524 nm，從半極化面奈米金字塔及空間解析陰極射線螢光得到發光方式，及使用有限元素法(Finite Element Method, FEM)模擬結果，並得到一致的結果。

In this thesis, we presented high indium content of green, olivine, amber emission semipolar {10-11} GaN-based nanopyramid light emitting diodes (LEDs) grown on c-plane GaN nanorod using selective area growth (SAG). First, we deposited silicon dioxide (SiO2) on GaN nanorod by plasma enhance chemical vapor deposition (PECVD), and the selective etching was used by Reactive Ion Etching (RIE). The side wall passivation layer formed from upper two step. Then, GaN nanopyramid was grown on nanorod by metal-organic chemical-vapor deposition (MOCVD) using SAG technique. We use spatial resolved cathodoluminescence (CL) to analysis the emission region and have a discussion. In the measurement of temperature dependent photoluminance (TDPL), the less localize state in semipolar plane emission energy verses temperature, the degree of polarize effect is about 22 meV of conversional structure and closed to zero of semipolar plane, the higher internal quantum efficiency (IQE) of 22% to 30% from the integral PL intensity. And the faster radiative lifetime by reducing the quantum confine Stark effect (QCSE) by the time-resolved photoluminesce (TRPL). Calculating the radiative lifetime by IQE and dynamic carrier lifetime, the semipolar green, olivine and amber, the dimensional of exciton emission in nanostructure will be fitted. Then, we use finite-difference time-domain (FDTD) to simulate the light extraction efficiency (LEE) enhancement of the conversional of pattern sapphire substrate (PSS) c-plane LED is about 45% and nanopyramid LED is about 147%. Finally, the L-I-V curves of nanopyramid LEDs were investigated by electroluminescence (EL) measurement. The emission peak was shifted from 664 nm to 524 nm and full-width at half maximum (FWHM) as function of injection current will be discussed. The emission region of nanopyramid will change by increasing the injection current, and it is the same result with finite element method (FEM) simulation.