Design, fabrication, and analysis of 17-18-percent efficient surface-passivated silicon solar cells

A simple analytical model has been developed which provides useful guidelines for fabricating high-efficiency silicon solar cells. Consistent with the model calculations, both surfaces of n
⁺
-p-p
⁺
solar cells were passivated by a thin layer of thermally grown SiO
2
. Oxide passivation resulted in 17.2-percent efficient solar cells on 4 Ω . cm base material. Passivated cells show about 3 mA/cm
²
increases in J
SC
, ∼20 mV improvement in V
OC
, and ∼2-percent increase in absolute cell efficiency compared to the counterpart 15.2-percent efficient unpassivated cells. The majority of improvement in V
OC
came from the emitter surface passivation, while both front- and back-surface passivation contributed to the increase in J
SC
. The emitter region should not be regarded as a "dead layer" because emitter surface passivation can increase the quantum efficiency at short wavelengths from 40 percent to greater than 75 percent.