Bulg. J. Phys. vol.22 no.3-4 (1995), pp. 023-029

Reduction of Oval Defect Density in Layers Grown by MBE

G. Sarov, C. Bahchedjiev, T. Popov, L. Dimitrova
Institute of Applied Physics, 59, Sankt Peterburg Blvd., 4000 Plovdiv, Bulgaria
Abstract. In this paper we describe the results of our work on the reduction of the oval defects in GaAs and AlGaAs layers, grown by MBE. Among the influence of such parameters as vacuum system condition, growth rate and substrate preparation, which are crytically discussed in brief, the main attention is given to two factors: (a) the quantity of Ga in pBN crucible and (b) the As4 flux. It is concluded that the density of the oval defects can be considerably decreased (more than 10 times) by using less than a half volume charged pBN crucible with Ga. The increase of As4 flow during MBE process creates small size (≈ 3 μm) α type defects without particulates in their cores. This kind of defects can be completely eliminated by maintaining As stabilized growth condition with just sufficient arsenic flux.

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