State-Of-The-Art Surface Passivation Of Boron Emitters Using Inline Pecvd Alox/Sinx Stacks For Industrial High-Efficiency Silicon Wafer Solar Cells

Extremely low emitter saturation current density (J(0e)) values of 6 and 45 fA/cm(2), respectively, are reported for 220 and 30 Omega/sq planar p(+) boron emitters passivated by an AlOx/SiNx stack deposited in an industrial plasma-enhanced chemical vapor deposition (PECVD) reactor. The thermal activation of the AlOx films is performed in a standard industrial fast firing furnace, making the developed passivation stack industrially viable. For textured p(+) emitters the J(0e) values are found to be 1.5 - 2 times higher compared to planar emitters. This excellent surface passivation is attributed to a high negative charge density of -(3-6)x10(12) cm(-2) in combination with a low interface defect density of similar to 10(11) eV(-1)cm(-2). Assuming a short-circuit current density of 40 mA/cm(2) and the ideal diode law, the J(0e) result for the 80 Omega/sq emitter represents a 1-sun open-circuit voltage limit of 736 mV at 25 degrees C.