1996 Fiscal Year Final Research Report Summary
Growth of p-type ZnS and fabrication of superlattice-structured ultraviolet LED and LD
| Project/Area Number |
07555415
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 試験 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | Yamaguchi University |
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Principal Investigator |
TAGUCHI Tsunemasa Yamaguchi University, Faculty of Engineering, Professor, 工学部, 教授 (90101279)
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| Co-Investigator(Kenkyū-buntansha) |
SAKAIDA Toshiaki Showa Denko, Chichibu Laboratory, Deputy Manager, 秩父研究所, 研究長
YAMADA Yoichi Yamaguchi University, Faculty of Engineering, Research Associate, 工学部, 助手 (00251033)
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| Project Period (FY) |
1995 – 1996
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| Keywords | UV light-emitting diode / UV laser diode / ZnS / p-type conductivity control / quantum well / superlattice / localized exciton / biexciton |
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| Research Abstract |
We have studied the growth and the conductivity control of ZnS epitaxial layrs by means of a low-pressure metalorganic chemical vapor deposition (MOCVD) technique and fabrication of ZnS-based light-emitting diodes (LEDs) and laser diodes (LDs) operating in the ultraviolet spectral region.
Using high-purity dimethylzinc and hydrogen sulfide gas sources, we have succeeded in growing high-quality cubic ZnS epitaxial layrs without residual donor impurity contamination. The photoluminescence spectrum was dominated by the radiative recombination of free excitons, and no notable luminescence band associated with self-activated (SA) and other deep centers was detected. In particular, the free-exciton luminescence was observed even at room temperature for the first time.
In order to achieve n-type conductivity control of ZnS,we chose iodine (I) as a donor impurity. We used a CH_3I gas and obtained electron concentration as high as 10^<19> cm^<-3>. It was found that iodine is one of the most suitable donor dopants for ZnS.On the other hand, in order to achieve p-type conductivity control, we chose nitrogen (N) as an acceptor impurity. We used monomethylamine and t-butylamine as a N source. Using a precracking technique, these sources were efficiently decomposed, and we obtained N acceptor concentration of 10^<17> cm^<-3>.
Ultraviolet LED and LD structures were fabricated using Cd_xZn_<1-x>S-ZnS strained layr superlattices and multiple quantum wells. Stimulated emission was observed at 375 nm under optical pumping condition at room temperature. This result strongly indicates that the ZnS-based structure is one of the most fruitful candidate for the application to ultraviolet light-emitting devices.
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