Control of doped layers in p–i–n microcrystalline solar cells fully deposited with HWCVD

Abstract

In this paper, the influence of the deposition conditions on the performance of p-i-n microcrystalline silicon solar cells completely deposited by Hot-Wire Chemical Vapour Deposition is studied. With this aim, the role of the doping concentration, the substrate temperature of the p-type layer and of amorphous silicon buffer layers between the p/i and i/n microcrystalline layers is investigated. Best results are found when the p-type layer is deposited at a substrate temperature of 125ºC. The dependence seen of the cell performance on the thickness of the i layer evidenced that the efficiency of our devices is still limited by the recombination within this layer, which is probably due to the charge of donor centres most likely related to oxygen.

Progress in single junction microcrystalline silicon solar cells deposited by Hot-Wire CVD

“…In spite of this fact, the efficiency of the best cells incorporating the intrinsic µc-Si:H layer deposited with HWCVD have reached 9.4% efficiency [1], which is close to the record of 10.1% achieved in µc-Si:H solar cells deposited using plasma techniques [16]. Besides, devices having all the µc-Si:H layers deposited by HWCVD have led to efficiencies above 5% [5,7,15]. In order to summarize the main aspects that influence the efficiency of solar cells deposited by HWCVD, two different approaches should be distinguished: the low substrate temperature approach (T s ≤ 350ºC) and the high temperature one (T s > 350ºC).…”

“…1 presents an overview of the evolution of the efficiency and the rest of the parameters obtained from the J(V) curve of µc-Si:H solar cells deposited by HWCVD, as a function of the year of publication of the result. The contributions included are from University of Barcelona [3][4][5], Forschungszentrum Jülich [1,6], University of Kaiserslautern [7], CNRS-École Polytechnique de Palaiseau [8,9], Utrecht University [10][11][12], Tokyo Institute of Technology [13,14] and National Renewable Energy Laboratory (NREL) [15]. µc-Si:H solar cells deposited with HWCVD have been developed during a much shorter period than that devoted to PECVD deposited ones.…”

Amorphous and Microcrystalline Silicon Solar Cells

“…Intrinsic microcrystalline silicon with a sufficiently high crystalline volume fraction (>45% as determined by Raman spectroscopy) does not show light-induced degradation of optoelectronic properties [130,131], whereas a-Si:H shows an increasing defect density upon light soaking (Staebler-Wronski effect [3]). Therefore, the microcrystalline bottom cell is often chosen to be current limiting, so that the tandem cell as a whole behaves more stably.…”