Epitaxially stacked structure for GaInP/GaInAs pseudomorphic TEGFET has been grown by low-pressure metal organic vapor-phase epitaxy (MOVPE) system. To obtain the enhanced mobility of TEG, GaInP spacer layer having the graded gallium (Ga) composition is employed. By inserting the spacer layer with the graded Ga composition, the mobility at room temperature is enhanced as high as 6300 cm(2)/V s with sheet carrier concentration of 1.4 x 10(12) cm(-2). Obtainable mobility reaches up to 32.000 cm(2)/V s at liquid-nitrogen temperature. Two-dimensional electron gas is also recognized to exist based on magneto-resistance behavior in the Shubnikov-de Haas (SDH) oscillation. The GaInP spacer layer having the graded Ga composition is effective to obtain high mobility of TEG in the GaInP/GaInAs stacking system for pseudomorphic TEGFET.