Microcrystalline/micromorph silicon thin-film solar cells prepared by VHF-GD technique

Abstract

Hydrogenated microcrystalline silicon prepared at low temperatures by the glow discharge technique is examined here with respect to its role as a new thin-"lm photovoltaic absorber material. XRD and TEM characterisations reveal that microcrystalline silicon is a semiconductor with a very complex morphology. Microcrystalline p}i}n cells with open-circuit voltages of up to 560}580 mV could be prepared.`Micromorpha tandem solar cells show under outdoor conditions higher short-circuit currents due to the enhanced blue spectra of real sun light and therefore higher e$ciencies than under AM1.5 solar simulator conditions. Furthermore, a weak air mass dependence of the short-circuit current density could be observed for such micromorph tandem solar cells. By applying the monolithic series connection based on laser patterning a "rst micromorph mini-module (total area of 23.6 cm) with 9% cell conversion e$ciency could be fabricated.

Relationship between Raman crystallinity and open-circuit voltage in microcrystalline silicon solar cells

“…An effect that is generally observed [4,21] when one increases the silane concentration used for the deposition of the i-layer is a steady increase in the V oc ; followed by an abrupt change close to the mc-Si:H/a-Si:H transition [7]. The evolution of V oc with silane concentration for the nip series deposited on sputtered ZnO is given in Fig.…”

“…In addition to these two series of nip-cells, some other nip cells not pertaining to these series, as well as a large set of pin cells (that can be considered to be typical products of our solar cell technology laboratory at IMT Neuch# atel) which cover a wide range of V oc values (see Ref. [4]) were also analysed both electrically and by Raman spectroscopy.…”

“…By decreasing the silane concentration SC=SiH 4 /(SiH 4 +H 2 ) down to a few percent, the material undergoes an a-Si:H/mc-Si:H transition. The value of SC used for the deposition of the intrinsic (i) layer has been shown to play a significant role in determining the highest so far attainable values for the open-circuit voltage (V oc ) of a pin cell [4]. On the other hand, it is well known that the material microstructure depends as well on silane concentration [1,5].…”

Thin film silicon solar cells for space applications: Study of proton irradiation and thermal annealing effects on the characteristics of solar cells and individual layers

“…Thin-film double-junction solar cells using amorphous silicon (a-Si:H) and microcrystalline silicon (mc-Si:H), i.e. the socalled ''micromorph'' tandem cells [3][4][5][6], are a further interesting candidate for use on satellites, but the proton radiation hardness of the microcrystalline material had so far not been thoroughly explored. The present paper intends to fill this gap, by reporting on corresponding proton irradiation tests and subsequent annealing experiments.…”

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

“…Recent results regarding µc-Si:H solar cells have shown that best device performance is found using µc-Si:H obtained in a regime close to the transition to amorphous growth [21,6]. This kind of material has a significant amount of amorphous tissue which can turn out to enhance the degradation of the device when exposed to long time illumination due to the so-called StaeblerWronski effect [22] (SWE).…”