Radio‐frequency (RF) sputtering is a low‐cost technique for the deposition of large‐area single‐phase AlInN on silicon layers with application in photovoltaic devices. Here, the effect of the Al mole fraction x from 0 to 0.56 on the structural, morphological, electrical, and optical properties of n‐AlxIn1−xN layers deposited at 550 ºC on p‐Si(100) by RF sputtering is studied. X‐ray diffraction data show a wurtzite structure oriented along the c‐axis in all samples, where the full width at half maximum of the rocking curve around the InN (0002) diffraction peak decreases from ≈9° to ≈3° while incorporating Al to the AlInN layer. The root‐mean‐square surface roughness, estimated from atomic force microscopy, evolves from 20 nm for InN to 1.5 nm for Al0.56In0.44N. Low‐temperature photoluminescence spectra show a blueshift of the emission energy from 1.59 eV (779 nm) for InN to 1.82 eV (681 nm) for Al0.35In0.65N according to the Al content rise. Hall effect measurements of AlxIn1−xN (0 < x < 0.35) on sapphire samples grown simultaneously point to a residual n‐type carrier concentration in the 1021 cm−3 range. The developed n‐AlInN/p‐Si junctions present promising material properties to explore their performance operating as solar cell devices.
Sputtering is a deposition technique used to fabricate low‐cost silicon films on crystalline and amorphous substrates. Herein, the deposition of amorphous silicon films by DC sputtering on both sapphire and GaN/sapphire substrates is reported. Films are deposited using argon plasma with a pressure of 0.47 Pa at 30–60 W of DC power and different deposition temperatures from RT to 550 °C. The effect of different deposition conditions is investigated on structural quality, layer morphology, and optical properties of the layers. X‐ray diffraction measurements do not show any peak associated to crystalline silicon, while energy‐dispersive X‐ray demonstrates the presence of silicon in the layers. Silicon films deposited on sapphire show a compact morphology but the formation of silicon columns on GaN. On both substrates, the growth rate increases a factor of 3 with the applied DC power (50–150 nm h−1). Finally, the optical bandgap energy extracted from transmission measurements decreases from 2.40 to 2.10 eV with the DC power, due to the reduction of impurity incorporation. This work offers a low‐cost alternative for the deposition of amorphous compact silicon films and silicon nanocolumns at low temperature, for application in sensing, photonic, electronic, and photovoltaic devices.
AlxIn1−xN ternary semiconductors have attracted much interest for application in photovoltaic devices. Here, we compare the material quality of AlxIn1−xN layers deposited on Si with different crystallographic orientations, (100) and (111), via radio-frequency (RF) sputtering. To modulate their Al content, the Al RF power was varied from 0 to 225 W, whereas the In RF power and deposition temperature were fixed at 30 W and 300 °C, respectively. X-ray diffraction measurements reveal a c-axis-oriented wurtzite structure with no phase separation regardless of the Al content (x = 0–0.50), which increases with the Al power supply. The surface morphology of the AlxIn1−xN layers improves with increasing Al content (the root-mean-square roughness decreases from ≈12 to 2.5 nm), and it is similar for samples grown on both Si substrates. The amorphous layer (~2.5 nm thick) found at the interface with the substrates explains the weak influence of their orientation on the properties of the AlxIn1−xN films. Simultaneously grown AlxIn1−xN-on-sapphire samples point to a residual n-type carrier concentration in the 1020–1021 cm−3 range. The optical band gap energy of these layers evolves from 1.75 to 2.56 eV with the increase in the Al. PL measurements of AlxIn1−xN show a blue shift in the peak emission when adding the Al, as expected. We also observe an increase in the FWHM of the main peak and a decrease in the integrated emission with the Al content in room-temperature PL measurements. In general, the material quality of the AlxIn1-xN films on Si is similar for both crystallographic orientations.
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