Research on New Properties by Binary/Binary Superlattices

在目前的研究中，晶体结构和新的物理现象。以AIAs/GaAs、InAs/GaAs和GaSb/GaAs超晶格为例，对基于新物理概念的二元/二元超晶格进行了研究。三个超晶格，在他们的平均组成，晶格匹配二进制化合物衬底：砷化镓和InP。然而，它们的无规合金的混相性却有很大的不同。在InAs/GaAs超晶格中，对其平均晶体结构和微观晶体结构进行了分析，并对其电子性能进行了理论计算。用MBE生长出m层InAs和n层GaAs的超晶格。m和n的组合为(m,n)=(6.45,0.51)、（8.8,1.3）和（2.2,1,2）.2。从（004）和（115）平面的x射线反射证实了晶体的平均结构是立方结构。建立了InGaAsP合金和InAs/GaAs超晶格的Ga和as吸收边的EXAFS测量方法。EXAFS分析表明，在(m,n)=(6.45,0.51)的超晶格中，Ga-As键长为2.51 A，比GaAs长2.4%。它甚至比In0.93Ga0.07As中的2.485 A还要长。结果表明，键。在无序合金和超晶格中，弛豫有很大的不同。对二维电子的能量态、波函数、散射机制和电子迁移率的理论研究表明，消除了随机合金中主要的合金散射，使电子迁移率比AIGaAs/GaAs单一异质结构高5倍。

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.