TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Method: In manufacturing a solar cell, the first semiconductor layer is formed in the semiconductor substrate and an upper surface of the irregularity structure by doping the semiconductor substrate and the upper surface of the irregularity structure with the second dopant. The first heat-treatment process is carried out at a temperature of 600 to 700 degrees C for 5 to 90 seconds so as to form the irregularity structure with a curved shape. The first heat-treatment process is carried out at a temperature of 600 to 700 degrees C for 90 to 120 seconds so as to form the irregularity structure with a curved shape and having a neck portion. It further comprises a reflection-preventing layer comprising silicon nitride, silicon oxynitride or silicon oxide on the first semiconductor layer, where the front electrode is electrically connected to the first semiconductor layer through the reflection-preventing layer. The reflection- preventing layer has an irregularity structure which is identical in position and shape to the irregularity structure on the first semiconductor layer. The first dopant is a P-type or N-type dopant. It further comprises: forming a rear electrode at an opposite side of the semiconductor substrate; and forming a second semiconductor layer at the opposite side of the semiconductor substrate through a second heat-treatment process, the second semiconductor layer doped with the first dopant at a concentration that is relatively higher than that of the first dopant in the semiconductor substrate; where the rear electrode is electrically connected to the semiconductor substrate through the second semiconductor layer. The silicon source gas comprises SiH4 or Si2H6. It also comprises: forming a first-irregularity structure on a surface of a semiconductor substrate doped with a first dopant; forming a second-irregularity structure on the first-irregularity structure; forming a first semiconductor layer doped with a second dopant in the semiconductor substrate with the first-irregularity structure and second-irregularity structure, where the second dopant is different from the first dopant; and forming a front electrode at one side of the semiconductor substrate, the front electrode electrically connected to the first semiconductor layer. Preferred Cell: The solar cell further comprises a reflection-preventing layer comprising silicon nitride, silicon oxynitride or silicon oxide on the first semiconductor layer; where the front electrode is electrically connected to the first semiconductor layer through the reflection-preventing layer. The reflection-preventing layer has an irregularity structure which is identical in position and shape to the irregularity structure in the first semiconductor layer. The first dopant is a P-type or N-type dopant. It further comprises: a rear electrode at an opposite side of the semiconductor substrate; and a second semiconductor layer at the opposite side of the semiconductor substrate, the second semiconductor layer doped with the first dopant at a concentration that is relatively higher than that of the first dopant in the semiconductor substrate; where the rear electrode is electrically connected to the semiconductor substrate through the second semiconductor layer. It also comprises: a semiconductor substrate doped with a first dopant; a first-irregularity structure on the semiconductor substrate; a second-irregularity structure on the first- irregularity structure; a first semiconductor layer doped with a second dopant in the semiconductor substrate with the first-irregularity structure and second-irregularity structure, where the second dopant is different from the first dopant; and a front electrode electrically connected to the first semiconductor layer.