| Project/Area Number |
03650018
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Applied materials
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| Research Institution | The University of Tokushima |
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Principal Investigator |
SAKAI Shiro Tokushima University,Electrical and Electronic Engineering Associate Professor, 工学部, 助教授 (20135411)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1992: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1991: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | GaAs on Si / Thermal stress / Light emitting diodes / Opto-electronic IC / Degradation / dislocation / 発光ダイオ-ド / 寿命 / CaAs on Si |
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| Research Abstract |
The thermal stress which is produced in GaAs grown on Si substrates by the thermal expansion coefficient mismatch between the two materials is known to introduce dislocation into GaAs during the cooling stage after the growth and to degrade lifetime of the light emitting devices on Si.We have proposed the new UCGAS(undercut GaAs on Si)structure to reduce the stress and the stress-induced dislocation.We have found that 1.complete stress relaxation is obtained only in the annealed UCGAS since the as-grown GaAs on Si is plastically deformed,2.the reduction in both the stress and the dislocation is obtained by growing the layer on the UCGAS.
The UCGAS LED(light emitting diodes)and LD(laser diodes)were successfully fabricated,and the LED lifetime is demonstrated to be more than 3000 hours which is the longest lifetime among the GaAs LED's that are ever fabricated on the Si substrates.On the contrarily,the conventional mesa-type LED which contains high stress degrades in 30 minutes. The degradation mechanism is investigated.It was shown that the degradation is caused by the increased density of the dislocation during operation.The thermal stress relaxation is quite essential to suppress the degradation.
The above findings were published in the papers listed in the reverse side of this abstract.
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