Transparent Conducting Oxide Contacts for n-i-p and p-i-n Amorphous Silicon Solar Cells

We investigate the effect of sputtered transparent conducting oxide (TCO) contacts on the device performance of ss/n-i-p/TCO and glass/SnO2/p-i-n/TCO/Ag solar cells. TCO materials ITO and ZnO are compared, and found to have very similar transparency at the same sheet resistance. Sputtering ZnO with O2 in the Ar reduces FF for ss/n-i-p-/ZnO devices, compared to sputtering without O2. This isattributed to an interface not bulk effect. Sputtering ITO with O2 on the same devices increases Jsc due to highter ITO transparency, compared to sputtering without O2, but has no effect on FF. Based on curvature in the J(V) curve around Voc, the ZnO/p layer contact appears to be non-ohmic. For p-i-n/TCO/Ag devices, .mu.c-Si n-layers have much higher Voc, Jsc, and FF for all variations of TCO/AGback reflectors compared to an a-Si n-layer. Devices with ITO/Ag have lower Voc and Jsc compared to devices with ZnO/Ag. Sputtering ZnO with O2 has no detrimental effect on devices with .mu.c-Si n-layers but severly reduces FF in devices with a-Si n-layers.