|1.Research Institution||Sophia University|
|2.Research Area||Physical and Engineering Sciences|
|3.Research Field||Exploratory Research on Novel Artificial Materials and Substances for Next-Generation Industries|
|4.Term of Project||FY 1997 〜 FY 2001|
|6.Title of Project||Research on Novel Optical Device Materials for the Wide Spectral Region|
|Name||Institution,Department||Title of Position|
|Katsumi, Kishino||Sophia University, Faculty of Science and Technology||Professor|
|Names||Institution,Department||Title of Position|
|Hajime, Asahi||Osaka University, Institute of Scientific and Industrial Research||Professor|
|Hideo, Kawanishi||Kohgakuin University, Department of Electronic Engineering||Professor|
|Fumio, Koyama||Tokyo Institute of Technology, Precision and Intelligence Laboratory||Professor|
9.Summary of Research Results
(1) Development of mid-visible wavelength (550-620nm) materials: Novel II-VI compounds of MgZnCdSe, BeZnTe
alloys, and the related superlattice materials on InP were developed. Applying these materials, the first lasing operations
of yellow-green semiconductor LDs (563nm), and long life LED operations over 2500 hours at 554-644nm have been
achieved. ZnCdTe/ZnTe LEDs on ZnTe substrates were developed to have the yellow emission around 587 nm.
(2) Development of novel optical communication wavelength materials: Novel Tl-contained III-V materials, such as TlInGaAs and TlInGaP, in which temperature insensitive bandgaps are expected, have been investigated. The temperature dependency of the bandgap was suppressed to be -0.03meV/K, which is one tenth of a conventional semiconductor, for example InAs. The first lasing operation of TlInGaAs/InP LDs has been demonstrated.
The growth technology of highly strained InGaAs QW structures has been established. By use of that, the InGaAs strained QW LDs with the longest lasing wavelength of 1.2μm have been fabricated demonstrating the low threshold currents as small as 100 A/cm2/well and the high characteristic temperature more than 200K.
Aiming to break through the limit of the conventional optical communication wavelength materials, AlN/GaN intersubband transition (ISBT) material have been demonstrated. To realize mono-layer order thickness control, the RF-MBE growth technology of nitride semiconductors has been established to grow GaN/AlN superlattices. In supelattices, the ISBTs were observed in the wavelength range of 1.07-1.6μm, where the value of 1.07 μm is the shortest wavelength in all ISBT researches. The FWHM of absorption spectrum was 61meV, which is the narrowest among nitride-based ISBT experiments. The first operation of AlN/GaN resonant tunneling diodes with a high peak-to-valley ratio more than 30 has also been achieved.
(3) Development of UV wavelength region materials: Novel B-contained nitride semiconductors such as BAlGaN on SiC substrates have been developed using MOCVD. Deep-UV emissions around 250nm were observed in the BAlGaN/AlN-MQW samples. The novel strain control technique by GaN/AlN multi-buffer layers has been developed.
(1)II-VI Semiconductor、(2)Highly Strained Quantum Well、(3)Nitride Semiconductor
(4)BAlGaN、(5)Tl-contained III-V Semiconductor、(6)Optical Devices
(7)Temperature independent wavelength、(8)Semiconductor Laser、(9)Intersubband Transition