|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1986 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1985 : ¥1,600,000 (Direct Cost : ¥1,600,000)
In the present stutdy, crystal structures and new physical phenomena. of binary/binary superlattices based on new physical concept were investigated, taking AIAs/GaAs, InAs/GaAs and GaSb/GaAs superlatices. Three superlattices, at their average compositions, lattice-match to binary compund substrates: GaAs and InP. However, the miscibility of their random alloys is significantly different. In InAs/GaAs superlattices, the analysis of the average and microscopic crystal structures and theoretical calculations of electronic properties are presented.
1. Superlattices of m-layer InAs and n-layer GaAs were grown by MBE. The comnination of m and n were (m,n)=(6.45,0.51), (8.8,1.3),and (2.2,1,2).
2. From the x-ray reflections by (004) and (115) planes it was confirmed that the average crystal structure is cubic.
3. EXAFS measurement was etablished for the Ga- and As-absorption edge of InGaAsP alloys and InAs/GaAs superlattices.
4. The analysis of EXAFS revealed that in the superlattice of (m,n)=(6.45,0.51) the Ga-As bond length was 2.51 A being longer than that in GaAs by 2.4%. It is even longer than 2.485 A in In0.93Ga0.07As. The results indicate the bond. relaxation is greatly different in random alloys and superlattices.
5. Theoretical study of energy state, wave-function, scattering mechanisms, and electron mobility for two-dimensional electrons shows that the alloy scattering which is predominant in random alloy is eliminated to give the electron mobility higher than that in AIGaAs/GaAs single heterostructure by the factor of 5.