亚微观团粒的半导体材料

亚微观团粒的半导体,是一种引人注目的材料,因其尺寸小而引起量子效应,表现出非同一般的特性.两个研究小组发表了生成特定大小的硫化铜(CdS)团粒的特殊方法. 截径为1-100nm胶状半导体微粒是一类介于孤立分子和固体之间的新材料,可用来研究由分子态向 大块状态的转变.研究表明,胶体半导体的光学性质与宏观晶体截然不同,它依赖于微粒的大小——即所谓量子尺寸效应.微粒咸小时,电子-空穴对受到局域限制,价带和导带中会产生分立的电子态,有效带隙增大,使材料光谱的吸收边发生向短波移动的“蓝移”,光跃迁的振荡强度减弱,还会出现分立的吸收带;…     

Atomic Diffusion in Cu/Si （111） and Cu/SiO2/Si （111） Systems by Neutral Cluster Beam Deposition

The Cu films are deposited on two kinds of p-type Si （111） substrates by ionized duster beam （ICB） technique. The interface reaction and atomic diffusion of Cu/Si （111） and Cu/SiO2/Si （111） systems are studied at different annealing temperatures by x-ray diffraction （XRD） and Rutherford backscattering spectrometry （RBS）. Some significant results are obtained： For the Cu/Si （111） samples prepared by neutral dusters, the interdiffusion of Cu and Si atoms occurs when annealed at 230℃. The diffusion coefficients of the samples annealed at 230℃ and 500℃ are 8.5 ×10^-15 cm^2.s^-1 and 3.0 ×10^-14 cm^2.s^-1, respectively. The formation of the copper-silicide phase is observed by XRD, and its intensity becomes stronger with the increase of annealing temperature. For the Cu/SiO2//Si （111） samples prepared by neutral dusters, the interdiffusion of Cu and Si atoms occurs and copper silicides are formed when annealed at 450℃. The diffusion coefficients of Cu in Si are calculated to be 6.0 ×10^-16 cm^2.s^-1 at 450℃, due to the fact that the existence of the SiO2 layer suppresses the interdiffusion of Cu and Si.