| 摘要 |
PURPOSE:To eliminate abnormal diffusion and obtain a low-cost cell by a method wherein, when a pn-junction is formed on a polycrystalline Si substrate of one conduction type by applying an impurity of opposite conduction type, laser annealing is operated after injecting ions. CONSTITUTION:p<+>-Type ions, which are n-type impurity, injected into p-type polycrystalline Si substrate 1, about several mm in grain diameter, and by annealing this, a stabilized pn-junction is obtained. At this time, for the injection of p<+>- type ions, the accelerating energy is set at 30keV, the ion injection current density at 10-100mA, and the number of ions at 10<15>/cm<2>. For annealing, a ruby laser of 1 GW is used. By applying pulse of about 20 ns by means of a Q switch, annealing is operated from the surface of substrate 1 to a depth of about 4mum. By this, no grain boundary diffusion occurs, and the junction surface becomes flat. As a result, a cell, with characteristics of curve factor 0.70 and open voltage 0.51V, can be obtained. |
