Title:	Novel AlxIn1-xN (x~0-0.60) on Si (111) Heterojunctions Deposited by RF Sputtering for Solar Cells
Author(s):	M. Sun, R. Blasco, S. Elamrani, J. Olea, A.F. Braña de Cal, F.B. Naranjo, S. Valdueza-Felip
Topic:	New Materials and Concepts for Photovoltaic Devices
Subtopic:	New Materials and Concepts for Cells and Modules
Event:	37th European Photovoltaic Solar Energy Conference and Exhibition
Session:	1BV.4.54
ISBN:	3-936338-73-6
Price:	0,00 EUR
Document(s):	poster

Abstract/Summary:

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Aluminum indium nitride (AlxIn1-xN) is a novel environmentally-friendly semiconductor alloy with potential applications in photovoltaic devices thanks to its tunable direct bandgap energy from the near-infrared (InN ~ 0.7 eV) to the ultraviolet (AlN ~ 6.2 eV), its high thermal and chemical stability, and its resistance to high-energy particles in harsh environments. In this work, AlxIn1-xN thin films (90-nm thick) were deposited on p-Si(111) substrates by radio-frequency sputtering to develop n-AlInN/p-Si solar cells. Particularly, we studied the influence of the Al content (x) on the material and photovoltaic properties of the n-p heterojunctions. The deposition temperature and In RF power were set to 550°C and 30 W, respectively, while the RF power applied to the Al target, PAl, was varied from 0 to 225 W to control the Al mole fraction of the alloy. X-ray diffraction data show a wurtzite structure oriented along the c-axis for all samples, with an Al content that increases linearly with PAl in the range of x~0-0.56, assuming fully relaxed layers. The FWHM of the rocking curve around the AlInN (0002) diffraction peak remains below 7.6° for all samples, achieving a minimum of 2.8° for the Al0.2In0.8N one. The root mean square surface roughness, estimated from atomic force microscopy, evolves from 32 nm for InN to 1.6 nm for AlInN layers. Optical transmission spectra measured in AlInN on sapphire samples deposited simultaneously under the same conditions show a blue-shift of the apparent optical absorption band edge from 1.73 eV to 2.56 eV, accordingly to the increase of Al content from x = 0 to 0.56. Strong room-temperature photoluminescence was recorded for InN and Al0.2In0.8N on Si(111) samples, pointing to an emission at 1.56 eV and 1.74 eV, respectively. A decrease of the residual n-type carrier concentration from 7.51021 cm-3 to 1.61019 cm-3, and an increase of the layer resistivity from 0.2 mΩ·cm for to 3.87 mΩ·cm was obtained for InN to Al0.45In0.55N on sapphire samples, respectively, using Hall Effect measurements.