Radiation-induced oscillatory magnetoresistance in a tilted magnetic field in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Ga</mml:mi><mml:mi mathvariant="normal">As</mml:mi><mml:mo>∕</mml:mo><mml:msub><mml:mi mathvariant="normal">Al</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mi mathvariant="normal">Ga</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:mi mathvariant="normal">As</mml:mi></mml:mrow></mml:math>devices

We examine the microwave-photoexcited magnetoresistance oscillations in a tilted magnetic field in the high-mobility two-dimensional electron system (2DES). In analogy to the 2D Shubnikov--de Haas effect, the characteristic field ${B}_{f}$ and the period of the radiation-induced magnetoresistance oscillations appear dependent upon the component of the applied magnetic field that is perpendicular to the plane of the 2DES. In addition, we find that a parallel component ${B}_{\ensuremath{\Vert}}$ in the range of $0.6&lt;{B}_{\ensuremath{\Vert}}&lt;1.2\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ at a tilt angle of $\ensuremath{\theta}=80\ifmmode^\circ\else\textdegree\fi{}$ leaves the oscillatory pattern essentially unchanged.