Chemical etching of boron-rich layer and its impact on high efficiency n-type silicon solar cells

This paper reports on an effective chemical etching treatment to remove a boron-rich layer which has a significant negative impact on n-type silicon (Si) solar cells with boron emitter. A nitric acid-grown oxide/silicon nitride stack passivation on the boron-rich layer-etched boron emitter markedly decreases the emitter saturation current density J _0e from 430 to 100 fA/cm ². This led to 1.6 increase in absolute cell efficiency including 22 mV increase in open-circuit voltage V _oc and 1.9 mA/cm ² increase in short-circuit current density J _sc. This resulted in screen-printed large area (239 cm ²) n-type Si solar cells with efficiency of 19.0.