SOLAR CELL AND MANUFACTURE THEREOF

摘要

PURPOSE:To decrease residual stress in a GaAs layer and minimize a warp in a wafer by forming the 1st and 2nd GaAs layers of 1st and 2nd conductivity types which act as functional layers one by one on the 1st principal surface of an Si substrate after forming a layer consisting of a substance which has a thermal expansion coefficient smaller than that of the Si substrate at a temperature approaching the normal temperature on the 2nd principal surface of the 1st conductivity type Si substrate. CONSTITUTION:An auxiliary layer 10 consisting of a substance which has a thermal expansion coefficient smaller than that of Si is formed at a temperature approaching the normal temperature on the 2nd principal surface 1b of an n-type Si substrate 1. When such a wafer obtained through the formation of the above layer 10 is heated up to a temperature at which a GaAs layer is formed, e.g. about 700 deg.C, the side of the Si substrate warps into a protrudent form by depending upon the difference between thermal expansion coefficients of Si and a material which forms the auxiliary layer 10. In such a state, an n-type GaAs layer 2, and a p-type GaAs layer 3 are formed by processes of MOCVD and MBE or the like. Subsequently, an epitaxial wafer that is free from warps as well as residual stress in the GaAs layer is obtained by taking out the wafer from a device for growing crystals at the normal temperature.