From the simulation, it can be expected that low Dorsomorphin supplier plasma power will result in uniform coverage. Although the measured minority lifetimes are shorter for the SiNW array with α-Si:H deposited at 15 W than those at 40 W, the largest V oc of 0.50 V was observed for 0.51-μm SiNW 3-MA supplier passivated at 15 W for 30 min. The largest V oc of 0.50 V is similar to the results obtained from the nanowire device demonstrated by Jia et al. [13, 14]. Nevertheless, the observed V oc value is still lower than that of SiMW solar cells [5–8]. It is suggested that the inhomogeneity of α-Si:H coverage and passivation on SiNWs along the vertical direction reduces the open circuit
voltage. On the other hand, the dependence of J sc on deposition time of α-Si:H Avapritinib molecular weight is opposite to V oc, as shown in Figure 5d. It was observed that the prolonged deposition time decreases the current density, which could be ascribed to the increase in the thickness of α-Si:H layers. It is always expected that the nanowire surface passivation is only required for very thin conformal shell layer
, in which the thicker amorphous shell may contribute to the higher resistance, degrading the carrier collection efficiency, parallel to the passivation of the nanowire surface dangling bonds. Although the reflectance measurement indicates that the 0.85-μm SiNW array has a lower reflectance, which means to have a more light trapping effect, the largest J sc was achieved for the 0.51-μm SiNW. Therefore, high photovoltaic conversion efficiency (PCE) was achieved in 0.51-μm SiNW solar cell with α-Si:H deposited at a power
of 15 W for 20 min. Comparison of EQE of the 0.85-μm SiNW cells is shown in Figure 7, which further illustrates the effect of α-Si:H coverage. EQE in the wavelength range of 700 to 1,100 nm is nearly the same for the four cells constructed in this study. However, EQE in the wavelength range of 400 to 600 nm shows a remarkable decrease with the increase of plasma power and deposition time. Figure 7 Comparison of external quantum efficiency of 0.85-μm SiNW solar cells. Conclusion Ketotifen In this work, we have analyzed the influence of deposition conditions and surface passivation properties of α-Si:H layer on the nanowire arrays. The thickness of α-Si:H layer and minority lifetime of the SiNW array was found to increase with the increase of deposition time and plasma power. The open circuit voltages of 0.85-μm SiNW solar cells increase with the deposition time and plasma power, while the open circuit voltage dependence of 0.51-μm SiNW solar cells seems to be contrary. The largest V oc of 0.50 V was observed for the 0.51-μm SiNW solar cell with α-Si:H passivation layer deposited at 15 W for 30 min. During the PECVD process, since the SiNWs were closely packed, the coverage of α-Si:H layer is inhomogeneous.