THE LIQUID PHASE EPITAXY OF SELF–ASSEMBLED InAsSbP–BASED STRAIN INDUCED ISLANDS ON InAs SUBSTRATES AND THEIR EVOLUTION FROM PYRAMIDS TO QUANTUM DOTS

The Liquid Phase Epitaxy technique has been applied for the formation on InAs (100) substrates self-assembled InAsSbP-based strain induced islands. The evaluation of these objects from pyramids to globe and quantum dots (QD) was detected and investigated. The Scanning Electron Microscope (SEM-EDAX – FEI Nova 600–Dual Beam) and Atomic Force Microscope (AFM – TM Microscopes–Autoprobe CP) equipments were used for the investigation of morphology, dimensions (size and shape), distribution density and composition of islands. The EDAX measurements on the top and bottom’s angles of InAsSbP quaternary pyramids as well as the lattice mismatch ratio calculations have been carried out. The compositions of quaternary InAs1-xySbxPy pyramids with the values of x < 4 at.% and y < 2 at.% were measured. The good symmetry of compositions and lattice mismatch ratio values in the both angles of cut pyramid’s base has been detected. Investigations shown, that the strength on the top of pyramids was less than on the bottom’s angles and that the size of islands becomes smaller when the lattice mismatch decreases. The average density of the QDs was equal (5-7) ×10 cm, with dimensions of 0, 7-12 nm in height and 20-80 nm in width. The Gaussian distribution of QD’s amount versus to their average diameter has been also detected. The critical size (L Critical ~ 500 nm) of InAsSbP-based strain induced pyramid’s shape transformation to globe was determined. Introduction In recent years, much research effort has been focused on quantum dots (QDs) and wires [1– 3] due to their modified density of states, fascinating optoelectronic properties and device applications in areas such as lasers, photodetectors and electronic devices. From the viewpoint of electronic device application, it is valuable to fabricate QD devices basing on the processing techniques which are compatible with the very large-scale integrated circuit. Among quantum dot and wire fabricating techniques, self-organized Stranski Krastanov method [4] is an important one