Effect of texturing and surface preparation on lifetime and cell performance in heterojunction silicon solar cells

Heterojunction solar cells have potential for very high device voltages and currents, yet this relies on correct preparation of wafer surfaces prior to amorphous silicon (a-Si) deposition. This paper investigates the preparation of wafer surfaces by NaOH texturing and thinning prior to a-Si intrinsic layer deposition. It is found that with a CP etch or low-temperature anneal, and with correct deposition parameters, effective wafer lifetimes in excess of 1 ms can be achieved, indicating excellent surface passivation. Low reflectance achieved following wafer texturing along with high wafer lifetime led to efficiencies in finished devices as high as 17.6%.