Abstract: In a pump impeller structure employing a plurality of vanes arranged on the periphery of an impeller hub in a substantially radial direction of a pump shaft having a driving connection with the impeller, each vane including a particular geometry of a pressure surface therein. The pressure surface is formed concave in such a manner as to increase an angle defined between two tangential lines on a point of the pressure surface, form the innermost end of the vane to the outermost end of the vane, one tangential line being perpendicular to a straight line drawn in the radial direction of the impeller from the center of the pump shaft to the point on the pressure surface and the other tangential line being drawn along the contour of the pressure surface, both of the tangential lines being included in a same rotational plane of the vane.

Abstract: A gallium arsenide field effect transistor having a gate electrode of an alloy type p-n junction comprises source and drain electrodes formed on an n-type gallium arsenide region, a gate electrode of metal such as zinc or cadmium or an alloy of zinc or cadmium and gold, silver, tin or indium formed between the source and drain electrodes on the gallium arsenide region and serving as an impurity to the n-type gallium arsenide region, a p-type region being formed immediately beneath the gate electrode in the n-type gallium arsenide region. The above described field effect transistor is manufactured by the steps of: forming a source and drain electrodes on the n-type gallium arsenide region, depositing the gate electrode of the said metal or alloy, and heating the gallium arsenide region at the temperature lower than the melting point of the metal or the alloy, thereby to form the p-type region immediately beneath the gate electrode.