Control of symmetric properties of metamorphic In _0.27 Ga _0.73 As layers by substrate misorientation

Abstract

Asymmetry in dislocation density and strain relaxation has a significant impact on device performance since it leads to anisotropic electron transport in metamorphic materials. So it is preferred to obtain metamorphic materials with symmetric properties. In this paper, we grew metamorphic In 0.27 Ga 0.73 As epilayers with symmetric low threading dislocation density and symmetric strain relaxation in two ⟨110⟩ directions using InAlGaAs buffer layers on 7 ∘ misoriented GaAs (001) substrates. To understand the control mechanism of symmetric properties of In 0.27 Ga 0.73 As layers by the substrate miscut angles, In 0.27 Ga 0.73 As grown on 2 ∘ and 15 ∘ misoriented substrates were also characterized as reference by atomic force microscopy, transmission electron microscopy, and high resolution triple axis x-ray diffraction. The phase separation and interaction of 60 ∘ misfit dislocations were found to be the reasons for asymmetry properties of In 0.27 Ga 0.73 As grown on 2 ∘ and 15 ∘ substrates, respectively. Photoluminescence results proved that the In 0.27 Ga 0.73 As with symmetric properties has better optical properties than the In 0.27 Ga 0.73 As with asymmetric properties at room temperature. These results imply that high quality metamorphic In 0.27 Ga 0.73 As can be achieved with controllable isotropic electron transport property.

Рост твердых растворов InAs-=SUB=-x-=/SUB=-Sb-=SUB=-1-x-=/SUB=- на отклоненных подложках GaAs(001) методом молекулярно-лучевой эпитаксии

“…Кроме того, несимметричность релаксации напряжений становится причиной развития морфологии ростовой поверхности [12,14]. Одним из эффективных методов подавления несимметричной релаксации напряжений является использование подложек, отклоненных от сингулярной грани [14][15][16].…”