|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1997 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1996 : ¥1,800,000 (Direct Cost : ¥1,800,000)
With this research grant, we have completed two work ; (1) metal In adsorption on GaAs (001) substrate, (2) quantum dots based on InAs/GaAs heteroepitaxy. For In adsorption on GaAs (001), we have observed two new surface reconstructions, 4x2/c (8x2) and 6x2/c (12x2). Based on obtained bias-dependent high resolution STM images, atomic models for these two structures are proposed. We further found that InAs growth on the GaAs substrate with both two structures proceeds in a novel layr-by-layr mode, which has significant consequences and can be used for fabrication of high-performance optoelectronic devices. For InAs/GaAs, we studied the shape, size, their statistical distribution and structure of InAs quantum dots formed on nominally flat GaAs (001) substrate in the regime of InAs overlayr thickness from 1.6 to 3ML,under standard MBE growth condition. The facetting planes predominantly reconstruct into (114) and (113) structures. We have obtained atomically resolved STM images of the facetted planes on the InAs dots, and propose the atomic models of the (113) -4x1 and (215) -1x1 facetted planes on the InAs quantum dots, which allow us to understand the formation mechanism of quantum dots in great detail. We attribute the formation of (113) and (114) Facetting to their small surface energy with respect to the nominal flat (100) and (111) surfaces, which can be used to understand self-organization mechanism of the quantum dots.