Fluoride/Oxide Super Hetero-nanostructures for Advanced Photonic Devices
Grant-in-Aid for Scientific Research (C)
|Allocation Type||Single-year Grants|
Electronic materials/Electric materials
|Research Institution||TOKYO INSTITUTE OF TECHNOLOGY|
WATANABE Masahiro Associate Professor, Department of Information Processing, Tokyo Institute of Technology, 大学院・総合理工学研究科, 助教授 (00251637)
|Project Period (FY)
2001 – 2002
Completed(Fiscal Year 2002)
|Budget Amount *help
¥3,100,000 (Direct Cost : ¥3,100,000)
Fiscal Year 2002 : ¥1,200,000 (Direct Cost : ¥1,200,000)
Fiscal Year 2001 : ¥1,900,000 (Direct Cost : ¥1,900,000)
|Keywords||Zinc oxide / Calcium fluoride / epitaxial growth / Ultra violet / photoluminescence / current injection luminescence / nanocrystal / photonic material / 紫外発光 / アクセプタ|
The purpose of this study is to demonstrate ultra violet (UV) light emission from nanometer size crystals of wide gap semiconductors such as zinc oxide (ZnO), or BeZnSe formed in single crystalline calcium fluoride (CaF_2), which is a wide band gap ionic material epitaxially grown on silicon substrate. Using the heterostructures, UV emitting devices based on tunneling injection through CaF_2 quantum barriers can be expected. And moreover, strong quantum confinement can be utilized due to large conduction band discontinuity at the heterointerface, which leads fascinating changes of electron-photon interaction from the bulk material.
Results obtained in this study are as follows.
1. Formation technique of nanocrystalline zinc oxide (ZnO) on CaF_2/Si(111) substrate has been developed using RF sputtering followed by regrowth of CaF_2 by molecular beam epitaxy. Growth temperature, background pressure, RF power and post annealing condition was optimized.
2. Ultra-violet photoluminescence at wav
elength of 380 nm and electroluminescence was observed at room temperature. Transmission electron microscopy (TEM) lattice image clearly confirmed that sharp heterointerface of CaF_2/ZnO/CaF_2 was formed. Growth condition was optimized by luminescence intensity and surface morphology.
3. Thermal annealing process in oxygen or ultra-high vacuum was introduced for improving luminescence intensity. Dependence of luminescence on annealing temperature, time, pressure was clarified.
4. Current injection luminescence was demonstrated using tunneling injection structure with transparent conducting ITO electrode fabricated using photolithography and dry etching. UV luminescence was clearly observed at room temperature and the luminescence was stable. From this result, nanocrystalline ZnO embedded in single crystalline CaF_2 has stable heterointerface, which is attractive for UV photonic materials on silicon substrate.
5. UV emission from BeZnSe grown on CaF_2/Si(111) has been demonstrated for the first time. The advantage of this material system is lattice matched with silicon substrate. Less
Research Products (12results)