GaN grown on {12-35} by using Dash Patterned Sapphire Substrate

• Main Authors: Lin,Chia-Chen, 林家振
• Other Authors: Wu,Yew-Chung
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/87735137935218225077

碩士 === 國立交通大學 === 材料科學與工程學系所 === 104 === Recently,Light-emitting diodes (LEDs) are widely used in lighting and display and gradually replace traditional light source.There are many methods for improving the internal quantum efficiency(IQE) and light extraction efficiency (LEE) and the PSS techmique has attracted much attention for its high production yield.Besides,using PSS technique can improve both IQE and LEE.The common substrate for LED is sapphire substrate and because its structure is hexagonal,the structure of GaN epi layer usually is wurtzite.Due to its structure,it will cause polarization field in [0001] direction and therefore has QCSE effect which will let IQE drop.According to the previous study,specific facet will be exposed after wet etching and that facet can grow zinc-blende GaN.The structure of zinc-blende GaN is cubic which will not cause QCSE effect in [0001] direction.So in our study we will use line mask to produce Dash Patterned Sapphire Substrate and analyze its crystal structure. In first part,we try to use line mask to produce line Patterned Sapphire Substrate but the {123 ̅5} did not appear after wet etching.In second part,we use the same mask to produce Dash Patterned Sapphire Substrate and we deposit SiO2 at the bottom of pattern to block GaNb growth.Then in third part we use Transmission electron microscope,TEM to analyze the GaN and find that the SiO2 can sucessfully block the growth of GaNb and let GaN grow from E facet {123 ̅5}.But from the results of Raman spectroscopy and Photoluminescence,PL we did not find the zinc-blende GaN.The reason why there is no zinc-blende GaN is probably because of the different epi condition and the metastable phase of zinc-blende GaN which will cause the growth of zinc-blende GaN in the first stage but transform to stable phase wurtzite GaN in the second stage.We also find the epi orientation between growing facet and GaN and it is (0001)_GaN∥(02 ̅22)_sapphire以及[112 ̅0]_GaN∥[21 ̅1 ̅0]_sapphire 。