Suppression of defect propagation in semiconductors by pseudomorphic layers
نویسندگان
چکیده
The propagation of defects in semiconductor heterostructures has been studied both theoretically and experimentally. The simple model shows that defects originating from lattice-matched regions can be prevented from entering, or can be trapped by, a pseudomorphic layer, depending on the signs of the strain induced by the defect and the strain in the pseudomorphic layer. A pseudomorphic layer can therefore prevent the defect from propagating across in and entering the critical active region of a device. Experimentally, the photoluminescence intensities of Ale,Gac6As/GaAs quantum wells with and without pseudomorphic InO,GacsAs layers for prevention of defect propagation have been compared. GaAs substrates of high etch pit density were used to generate defects below the quantum well and silicon implantation was used to generate defects above it. The elevated temperatures during molecular-beam-epitaxial growth and postimplant rapid thermal annealing serve to assist in defect propagation in the respective regions of the heterostructure. The structures with pseudomorphic Inc,GacsAs layers consistently showed much higher quantum-well photoluminescence intensities than those without the pseudomorphic layers. These results indicate smaller defect densities in the quantum wells with pseudomorphic layers and strongly support the defect propagation model.
منابع مشابه
Direct energy gap group IV semiconductor alloys and quantum dot arrays in SnxGe1−x/Ge and SnxSi1−x/Si alloy systems
The narrow gap semiconductor alloys SnxGe1−x and SnxSi1−x offer the possibility for engineering tunable direct energy gap Group IV semiconductor materials. For pseudomorphic SnxGe1−x alloys grown on Ge (001) by molecular beam epitaxy, an indirect-to-direct bandgap transition with increasing Sn composition is observed, and the effects of misfit on the bandgap analyzed in terms of a deformation p...
متن کاملInvestigation of HF/H2O2 Concentration Effect on Structural and Antireflection Properties of Porous Silicon Prepared by Metal-Assisted Chemical Etching Process for Photovoltaic Applications
Porous silicon was successfully prepared using metal-assisted chemical etching method. The Effect of HF/H2O2 concentration in etching solution as an affecting parameter on the prepared porosity type and size was investigated. Field emission electron microscopy (FE-SEM) confirmed that all etched samples had porous structure and the sample which was immersed into HF/H2O2 withmolar ratio of 7/3.53...
متن کاملMorphology, Structure, and Optical Properties of Semiconductor Films with GeSiSn Nanoislands and Strained Layers
The dependences of the two-dimensional to three-dimensional growth (2D-3D) critical transition thickness on the composition for GeSiSn films with a fixed Ge content and Sn content from 0 to 16% at the growth temperature of 150 °С have been obtained. The phase diagrams of the superstructure change during the epitaxial growth of Sn on Si and on Ge(100) have been built. Using the phase diagram dat...
متن کاملHigh Perfection Approaches to Si-based Devices through Strained Layer Epitaxy
1. Introduction In developing materials and processes for VLSI, the demands of high manufacturing yield make it necessary to consider approaches which are inherently capable of creating structures without defects. For example, the success of the well-known Si/SiGe/Si HBT relies on pseudomorphic strained layers below critical thickness to avoid misfit dislocations. Similarly, since the role of s...
متن کامل