کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1484710 | 1510525 | 2008 | 6 صفحه PDF | دانلود رایگان |
In this study, we have developed and applied deposition phase diagrams in the plane of the bulk layer thickness db and the H2-dilution ratio R = [H2]/[Si2H6] for Si:H materials deposited by 70 MHz VHF PECVD from [H2] + [Si2H6] mixed gases on c-Si/(native-oxide)/n-layer substrates. To establish the phase diagrams, series of Si:H depositions having different R values over the range of 60–150 were measured in real time using a rotating-compensator multichannel ellipsometer. Using phase diagram concepts for guidance, we have fabricated high efficiency single-junction nc-Si:H n–i–p solar cells with ∼3 Å/s intrinsic layers using the VHF PECVD process. We have found that the nc-Si:H solar cells with the best performance are obtained by incorporating i-layers deposited in the single-phase nanocrystalline silicon regime near the transition boundary to mixed-phase (a + nc)-Si:H. Applying insights from real time spectroscopic ellipsometry moreover, we have investigated in detail the effects of the phase of the underlying n-layer on the phase evolution of the overdeposited Si:H i-layer and on the overall device performance. With the strategy developed here, a stabilized efficiency of η = 9.46% (Voc = 0.516 V, Jsc = 24.65 mA/cm2, FF = 0.744) has been achieved for nc-Si:H solar cells (0.25 cm2 in active area) fabricated with an i-layer deposition rate of ∼2.2 Å/s.
Journal: Journal of Non-Crystalline Solids - Volume 354, Issues 19–25, 1 May 2008, Pages 2397–2402