Impact of sputter-induced ion bombardment at the heterointerfaces of a-Si:H/c-Si solar cells with double-layered In₂O₃:Sn structures

Abstract

The effect of ion bombardment on photovoltaic characteristics, induced during the sputtering deposition of In 2 O 3 :Sn (ITO) layers, has been investigated using hydrogenated amorphous silicon/crystalline silicon (a-Si:H/c-Si) heterojunction solar cells with double-layered ITO structures. The experimental results indicate that the significant decrease in the fill factor (FF) induced at a sputtering rf power higher than 30 W is attributed to the increase in series resistance (R s ), which is caused by property degradation in the ITO/a-Si:H interface region. Furthermore, it has been found that the impact of the sputter-induced ion bombardment on the property degradation reaches the ITO/a-Si:H interface region through the deposited ITO layer even up to a thickness of 20 nm.

Characterization of transparent conductive oxide films and their effect on amorphous/crystalline silicon heterojunction solar cells

“…These three types of TCOs are commonly used in SHJ solar cells. 6,9,[17][18][19] In this work, the dopant concentrations were 1.0 wt % WO 3 , 5.0 wt % SnO 2 , and 3.0 wt % TiO 2 for IWO, ITO, and ITiO, respectively.…”

“…Therefore, a TCO film with excellent optical and electrical properties is vital for SHJ solar cells. In addition, many researchers reported [6][7][8][9][10][11][12] that the soft deposition of TCO films is necessary in preventing damage on the as-deposited ultrathin a-Si:H film [the intrinsic layer is around 5 nm and the doped layer (p or n) is around 10 nm] of SHJ solar cells. It has been reported that the higher quality of TCO films fabricated by reactive plasma deposition (RPD) originates from the lower energy of depositing particles than of sputtering.…”

“…It has been reported that the higher quality of TCO films fabricated by reactive plasma deposition (RPD) originates from the lower energy of depositing particles than of sputtering. [13][14][15][16] During RPD-TCO deposition, the energy required to deposit particles is less than 40 eV; the particles with superhigh energies exceeding 100 eV were observed during sputter-TCO deposition. 14) In fact, TCO films for SHJ solar cells are usually deposited by plasma particles with energies of 10-20 eV during RPD.…”

Effects of sputtering pressure and temperature of ITO electrodes on the performance of p-BaSi2/n-Si heterojunction solar cells

“…[22][23][24] In Si solar cells, there have been reports showing that the solar cell performance depends on the deposition conditions of ITO layers. [25][26][27][28] For example, in heterojunction Si with intrinsic thin layer solar cells, 26) ITO electrodes deposited at room temperature (RT), lead to a very low open-circuit voltage V OC due to the passivation degradation of thin-film hydrogenated a-Si layers underneath probably resulting from particle bombardment during the ITO sputtering. Therefore, ITO sputtering is performed at elevated temperatures like 180 °C to recover some of the degradation induced by the ITO sputtering, resulting in an improvement of V OC .…”

Effects of indium tin oxide on the performance of heterojunction silicon wafer solar cells

“…14,17,[19][20][21] Besides the optoelectrical properties of ITO films, sputter damage is another typical problem associated with the deposition process and has been widely reported. 22,23) It is generally believed that during the ion bombardment sputtering of ITO films, the transfer of energy from ions to the substrate generates defects in the crystalline silicon (c-Si) network, which thus deteriorates the c-Si surface passivation provided by a-Si:H. 24,25) Hence, an unsuitable ITO deposition process can severely limit the conversion efficiency of HET solar cells. 26) However, for most of the above-mentioned highefficiency HET solar cells, little information is available on the transparent conductive layer preparation conditions and their effects on the conversion efficiency of the solar cells.…”