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The effect of solutal Marangoni convection on flow instabilities in the presence of thermal Marangoni convection in a Si-Ge liquid bridge with different aspect ratios <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>A</mi><mi>s</mi></msub></semantics></math></inline-formula> has been investigated by three-dimensional (3D) numerical simulations under zero gravity. We consider a half-zone model of a liquid bridge between a cold (top plane) and a hot (bottom plane) disks. The highest Si concentration is on the top of the liquid bridge. The aspect ratio (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>A</mi><mi>s</mi></msub></semantics></math></inline-formula>) drastically affects the critical Marangoni numbers: the critical solutal Marangoni number (under small thermal Marangoni numbers (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>M</mi><msub><mi>a</mi><mi mathvariant="normal">T</mi></msub><msub><mi>A</mi><mi>s</mi></msub><mo>≲</mo><mn>1800</mn></mrow></semantics></math></inline-formula>)) has the same dependence on <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>A</mi><mi>s</mi></msub></semantics></math></inline-formula> as the critical thermal Marangoni number (under small solutal Marangoni numbers (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>400</mn><mo>≲</mo><mi>M</mi><msub><mi>a</mi><mi mathvariant="normal">C</mi></msub><msub><mi>A</mi><mi>s</mi></msub><mo>≲</mo><mn>800</mn></mrow></semantics></math></inline-formula>)), i.e., it decreases with increasing <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>A</mi><mi>s</mi></msub></semantics></math></inline-formula>. The azimuthal wavenumber of the traveling wave mode increases as decreasing <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>A</mi><mi>s</mi></msub></semantics></math></inline-formula>, i.e., larger azimuthal wavenumbers (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>m</mi><mo>=</mo><mn>6</mn><mo>,</mo><mn>7</mn><mo>,</mo><mn>11</mn><mo>,</mo><mn>12</mn></mrow></semantics></math></inline-formula>, and 13) appear for <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>A</mi><mi>s</mi></msub><mo>=</mo><mn>0.25</mn></mrow></semantics></math></inline-formula>, and only <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>m</mi><mo>=</mo><mn>2</mn></mrow></semantics></math></inline-formula> appears when <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>A</mi><mi>s</mi></msub></semantics></math></inline-formula> is one and larger. The oscillatory modes of the hydro waves have been extracted as the spatiotemporal structures by using dynamic mode decomposition (DMD). The present study suggests a proper parameter region of quiescent steady flow suitable for crystal growth for smaller aspect ratios of the liquid bridge.