Growth of bulk single crystals under applied magnetic field by liquid phase electroepitaxy

Abstract

Binary (GaAs) and ternary (InGaAs) bulk single crystals have been grown by the growth process of liquid phase electroepitaxy (LPEE with and without the application of an external static magnetic field. Two significant achievements were made: first is the development of a new, improved LPEE system to grow, flat, thick and uniform single crystals of In 0.04Ga 0.96As, and the second is the significant improvement of the LPEE growth rate by the application of an external static magnetic field. Experiments performed under no magnetic field have shown that LPEE can grow large (thick) and flat single crystals of In 0.04Ga 0.96As with uniform composition. Experiments have also proved the reproducibility of LPEE growth of such single crystals in terms of crystal thickness, flatness, and compositional uniformity. It was possible to use higher electric current density levels (up to 7 A/cm 2) in spite of the achievement of large crystal thicknesses. Experiments conducted under various magnetic field levels have shown that the LPEE growth process at the 4.5 kG and lower magnetic field levels yields satisfactory growth. However, the growth experiments at higher magnetic field and electric current density levels were unsatisfactory and unstable. Although the crystals were still grown, large holes and unstable interfaces were observed in the grown crystals. However, lower magnetic field and electric current levels had very beneficial effects, namely flat growth interfaces and prolonged growth due to weak convection in the liquid zone, and a substantial increase in the growth rate (about up to 20 times higher at 4.5 kG and 7 A/cm 2 levels). Such a significant increase in the growth rate under a static magnetic field can be attributed to the positive effect of applied magnetic field on the mechanism of “electromigration”. The performed electron probe micro analysis (EPMA) and the energy dispersive X-ray spectroscopy (EDS) measurements have shown that the indium composition distribution in grown crystals was uniform in both the radial and growth directions. Advances made through this work may be considered as a significant initial step towards the commercialization of the LPEE technique for growth of high-quality, bulk single crystals.