NOVELTY - The method involves maintaining a predetermined distance between a solid-phase vapor source in a chamber and an absorbing layer precursor on a substrate in the chamber. The solid-phase vapor source contains tin and the absorbing layer precursor contains copper, zinc, tin and sulfur. The temperature rises inside the chamber to a forming temperature, so that the absorbing layer precursor forms an absorbing layer on the substrate. The temperature in the chamber is equal or lower than the forming temperature before maintaining the predetermined distance.    USE - Method for fabricating absorbing layer of solar cell.    ADVANTAGE - The solid-phase vapor source is adapted for inhibiting tin effusing from the absorbing layer precursor and maintaining the proportion of tin in the absorbing layer formed from the absorbing layer precursor. Therefore, during the fabrication process of the absorbing layer of the solar cell, the absorbing layer comprising a single crystal form is formed. Thus, the problem that different crystal forms is generated due to the effusion of the element in the absorbing layer is solved and the elements in the absorbing layer, fabricated after the solid vapor source is uniformly distributed, as well the transformation efficiency of the absorbing layer is improved. When the tin effuses from the absorbing layer precursor, the tin in the vapor is capable of compensating for the effusion of the tin from the absorbing layer precursor, so that the tin effusing from the absorbing layer precursor is avoided.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a thermal treatment device.    DESCRIPTION OF DRAWING(S) - The drawing shows a flowchart illustrating the method for fabricating absorbing layer of solar cell.    Step for arranging substrate in chamber (S101)    Step for arranging solid-phase vapor source in chamber (S102)    Step for separating solid-phase vapor source from absorbing layer precursor by predetermined distance (S103)    Step for performing heating process so that solid-phase vapor source vaporizes and transforms into vapor (S104)