Thin‐film silicon solar cell technology

Abstract

This paper describes the use, within p–i–n‐ and n–i–p‐type solar cells, of hydrogenated amorphous silicon (a‐Si:H) and hydrogenated microcrystalline silicon (μc‐Si:H) thin films (layers), both deposited at low temperatures (200°C) by plasma‐assisted chemical vapour deposition (PECVD), from a mixture of silane and hydrogen. Optical and electrical properties of the i‐layers are described. These properties are linked to the microstructure and hence to the i‐layer deposition rate, that in turn, affects throughput in production. The importance of contact and reflection layers in achieving low electrical and optical losses is explained, particularly for the superstrate case. Especially the required properties for the transparent conductive oxide (TCO) need to be well balanced in order to provide, at the same time, for high electrical conductivity (preferably by high electron mobility), low optical absorption and surface texture (for low optical losses and pronounced light trapping). Single‐junction amorphous and microcrystalline p–i–n‐type solar cells, as fabricated so far, are compared in their key parameters (Jsc, FF, Voc) with the [theoretical] limiting values. Tandem and multijunction cells are introduced; the μc‐Si: H/a‐Si: H or [micromorph] tandem solar cell concept is explained in detail, and recent results obtained here are listed and commented. Factors governing the mass‐production of thin‐film silicon modules are determined both by inherent technical reasons, described in detail, and by economic considerations. The cumulative effect of these factors results in distinct efficiency reductions from values of record laboratory cells to statistical averages of production modules. Finally, applications of thin‐film silicon PV modules, especially in building‐integrated PV (BIPV) are shown. In this context, the energy yields of thin‐film silicon modules emerge as a valuable gauge for module performance, and compare very favourably with those of other PV technologies. Copyright © 2004 John Wiley & Sons, Ltd.

Controlling the resistivity gradient in aluminum-doped zinc oxide grown by plasma-enhanced chemical vapor deposition

“…9 Moreover, ZnO is chemically and thermally stable in hydrogen-containing plasmas, which are employed, in the presence of SiH 4 gas, for the deposition of silicon-based thin film p-i-n junctions. [10][11][12][13] Therefore, impurity-doped ZnO, e.g., ZnO:Al, is considered to be an attractive candidate to replace ITO. 8 There are several deposition techniques applied to synthesize ZnO, such as sol-gel, 14 spray pyrolisis, 15 magnetron sputtering, [16][17][18] pulsed laser deposition, 19,20 atomic layer deposition, 21,22 and metalorganic chemical vapor deposition (MO-CVD).…”

Thin-film silicon solar cells with efficient periodic light trapping texture

“…Steep structures result in a strong blue response as observed in concepts with naturally rough grown ZnO. 22 For a fixed ␣ of ϳ100°the blue response decreases with increasing lateral structure sizes, as indicated by the arrow in Fig. 3.…”

Broadband light management using low-Q whispering gallery modes in spherical nanoshells

“…4d). This is because the absorption coefficient of nc-Si in this region is high ( > 1×10 5 cm − 1 ) 39 ; therefore, all of the light loss can be attributed to light reflection. As the top surfaces of samples with different numbers of layers (Fig.…”