成果報告書詳細
管理番号20130000000741
タイトル*平成24年度中間年報 ナノテク・先端部材実用化研究開発 InGaN系ナノコラム結晶による新世代映像表示デバイスの開拓
公開日2013/10/1
報告書年度2012 - 2012
委託先名セイコーエプソン株式会社 学校法人上智学院
プロジェクト番号P05023
部署名電子・材料・ナノテクノロジー部
和文要約
英文要約The development project named “Development of New-generation Projection Display Devices by InGaN-based Nanocolumn Crystals” started in fiscal year 2010. We are aiming to develop the fundamental technology of nanocolumn LED panels for the new method of projection display presented in this project, studying five research subjects, i.e. (1) verification of superiority in emission efficiency of the nanocolumn crystals, (2) green/red-light nanocolumn LEDs, (3) device process technology for nanocolumn LEDs, (4) array process and light emission from nanocolumn LED arrays, and (5) nano-pattern technology for large area nanocolumn LEDs. The interim findings in the fiscal year 2012 are briefly summarized as follows.
a) Photoluminescence (PL) properties of red-emitting (600 nm in wavelength) InGaN-based nanocolumn arrays were investigated to estimate the 300 K internal quantum efficiency (IQE). PL integrated intensities of the nanocolumns at 4 and 300K were larger than that of MOCVD-grown InGaN/GaN multiple-quantum-well reference sample, as factors of 3.3 and 3, respectively. The PL efficiencies of the nanocolumn (the ratio of PL integrated intensity to the excitation intensity) were evaluated at 4 and 300 K as a function of optical excitation density; the 4 K PL efficiency remains constant in a certain optical excitation density region. Assuming that the saturated plots represent an IQE of 100%, the IQE of the nanocolumn at 300 K was estimated to be 15-22%.
b) Ti nano-hole patterns, which were prepared on GaN templates through newly developed etching process contributed to the fabrication of uniformly arrays of pn-junction InGaN-based nanocolumns for the pattern area of 400400 m2; the occurrence probability of defective nanocolumn growth was 0.002%, i.e. 6 defects occurred for 150150 m2 area.
c) Red-emitting InGaN-based nanocolumn LEDs, which had circular ITO transparent electrodes with 100 nm diameter, operated at 633 nm in wavelength. The spectral FWHM was 60nm; the small spectral blue shift of 5 nm was observed for the increased injection current density from 65 to 255 A/cm2.
d) For InGaN-based nanocolumn LEDs fabricated in the last fiscal year, the current leakage occurred through the growth imperfection area and nanocolumn side wall. In this year, therefore we developed the side-wall passivation technique, in which Al2O3 films (30 nm in thickness) were deposited on the nanocolumn side-walls using atomic-layer-deposition (ALD) to suppress the leakage current. The light output of 155 W was observed for nanocolumn LEDs with the emission area of 30 m diameter.
e) Various process technologies were developed, i.e. dry etching for dividing the nanocolumn region into pixels, electrical insulation in which pixels are embedded in polymide, and matrix wiring between anode and cathode. Using the technologies, 4x4 LED pixel arrays were fabricated, observing light emissions of individual 2020 m2 nanocolumn LED pixels.
f) Two-beam interference lithography was developed to form square-lattice nanohole Ti-mask patterns on the whole surface of 2 inch GaN template. The lattice constant was 250 nm. However the nanohole pattern fabricated included a large number of vacancies of nanohole; thus, the improved spatial uniformity of exposure amount is essential to suppress occurrence of nanohole vacancies.
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