Rapid Thermal Annealing Effects on Passivation Quality of p-TOPCon Silicon Solar Cells

Unlike the traditional tube-furnace annealing at 875 °C, rapid thermal annealing (RTA) and laser annealing offer flexibility, high throughput, and control of the heating and cooling rates and holding times for effective crystallization, dopant activation, and passivation quality in the B-doped p-TOPCon device. A comprehensive scientific understanding of the effects of RTA is required. Slower RTA heating (≤ 798 K/min) and cooling (≤ 156 K/min) rates and optimal 60 s holding time at 825 °C enhanced the passivation quality, which was further improved by postanneal forming gas annealing (FGA). Faster heating and cooling rates (≥ 4800 K/min) damaged the passivation quality irreversibly and did not improve further by FGA. The optimized RTA parameters yielded iV _oc of 638 mV and sheet resistance of ∼1.0 kΩ/sq. The dopant activation was independent of the heating and cooling rates.