14 research outputs found
High In-content InGaN layers synthesized by plasma-assisted molecular-beam epitaxy: growth conditions, strain relaxation and In incorporation kinetics
We report the interplay between In incorporation and strain relaxation
kinetics in high-In-content InxGa1-xN (x = 0.3) layers grown by plasma-assisted
molecular-beam epitaxy. For In mole fractions x = 0.13-0.48, best structural
and morphological quality is obtained under In excess conditions, at In
accumulation limit, and at a growth temperature where InGaN decomposition is
active. Under such conditions, in situ and ex situ analysis of the evolution of
the crystalline structure with the growth thickness points to an onset of
misfit relaxation after the growth of 40 nm, and a gradual relaxation during
more than 200 nm which results in an inhomogeneous strain distribution along
the growth axis. This process is associated with a compositional pulling
effect, i.e. indium incorporation is partially inhibited in presence of
compressive strain, resulting in a compositional gradient with increasing In
mole fraction towards the surface
Influence of the AlN interlayer thickness on the photovoltaic properties of in-rich AlInN on Si heterojunctions deposited by RF sputtering
8 pags., 5 figs., 1 tab.We report the influence of the AlN interlayer thickness (0-15 nm) on the photovoltaic properties of AlInN on Si heterojunction solar cells deposited by radio frequency sputtering. The poor junction band alignment and the presence of a 2-3 nm thick amorphous layer at the interface mitigates the response in devices fabricated by direct deposition of n-AlInN on p-Si(111). Adding a 4-nm-thick AlN buffer layer improves the AlInN crystalline quality and the interface alignment leading to devices with a conversion efficiency of 1.5% under 1-sun AM1.5G illumination. For thicker buffers the performance lessens due to inefficient tunnel transport through the AlN. These results demonstrate the feasibility of using In-rich AlInN alloys deposited by radio frequency sputtering as novel electron-selective contacts to Si-heterojunction solar cells.Support from projects NitPho (TEC2014-60483-R), ANOMALOS (TEC2015-
71127-C2-2-R), INFRASIL (TEC 2013-41730-R), SINFOTON (S2013/MIT 2790), MADRID-PV
(2013/MAE-2780), PhotoAl (CCG2015/EXP-014), PAI research group (TEP-946 INNANOMAT),
and FEDER-EU is acknowledged. TEM data were taken at DME-SC-ICyT-UCA. A. Nuñez- Ë
Cascajero thanks her grant to the University of Alcala and D. Montero acknowledges his contract ÂŽ
BES-2014-067585
Influence of the AlN interlayer thickness on the photovoltaic properties of In-rich AlInN on Si heterojunctions deposited by RF sputtering
We report the influence of the AlN interlayer thickness (0-15 nm) on the
photovoltaic properties of Al0.37In0.63N on Si heterojunction solar cells
deposited by radio frequency sputtering. The poor junction band alignment and
the presence of a 2-3 nm thick amorphous layer at the interface mitigates the
response in devices fabricated by direct deposition of n-AlInN on p-Si(111).
Adding a 4-nm-thick AlN buffer layer improves the AlInN crystalline quality and
the interface alignment leading to devices with a conversion efficiency of 1.5%
under 1-sun AM1.5G illumination. For thicker buffers the performance lessens
due to inefficient tunnel transport through the AlN. These results demonstrate
the feasibility of using In-rich AlInN alloys deposited by radio frequency
sputtering as novel electron-selective contacts to Si-heterojunction solar
cells
Infrared SPR sensing with III-nitride dielectric layers
6 pågs.; 6 figs.© 2015 Elsevier B.V. In this work, Aluminum Indium Nitride (AlxIn1-xN) has been used as the dielectric overlay for a surface plasmon resonance sensor. The use of a ternary compound such as AlxIn1-xN for the dielectric allows a fine tuning of its refractive index by varying its composition, thus improving the sensor performance. Narrower transmittance resonances and higher sensitivities are obtained for transducers where the substrate rotates while depositing the ternary compound, which is attributed to the deposition of ternary layers with enhanced homogeneity. The calculated average sensitivity of the devices increases when rising the Al content of the dielectric layer, it being of 4360 nm/RIU, 5230 nm/RIU and 5730 nm/RIU for 0%, 36% and 100%, respectively. The device grown with 36% of Al shows the highest coupling strength. These results show the suitability of AlxIn1-xN compounds as dielectric layers in SPR sensors. © 2015 Elsevier B.V. All rights reserved.This work has been partially supported by the Spanish Government projects TEC2012 37958 C02 01 and TEC2014-58843-R, the Community of Madrid project S2013/MIT 2790 and the Alcalå University project CCG2014/EXP 051. Partial financial support was provided by the FPI Grant from the Alcalå University.Peer Reviewe
Morphology and arrangement of InN nanocolumns deposited by radio-frequency sputtering: Effect of the buffer layer
International audienc
Morphology and arrangement of InN nanocolumns deposited by radio-frequency sputtering: effect of the buffer layer
We present the structural and optical properties of (0001)-oriented nanocolumnar films of InN deposited on c-sapphire substrates by radio-frequency reactive sputtering. It is observed that the column density and dimensions are highly dependent on the growth parameters of the buffer layer. We investigate four buffer layers consisting of (i) 30 nm of low-growth-rate InN, (ii) 30 nm of AlN deposited on the unbiased substrate (us), (iii) 30 nm of AlN deposited on the reverse-biased substrate (bs), and (iv) a 60-nm-thick bilayer consisting of 30-nm-thick bs-AlN deposited on top of 30-nm-thick us-AlN. Differences in the layer nucleation process due to the buffer layer induce variations of the column density in the range of (2.5-16)Ă10 cm, and of the column diameter in the range of 87-176 nm. Best results in terms of mosaicity are obtained using the bs-AlN buffer layer, which leads to a full width at half-maximum of the InN(0002) rocking curve of 1.2°. A residual compressive strain is still present in the nanocolumns. All samples exhibit room temperature photoluminescence emission at âŒ1.6 eV, and an apparent optical band gap at âŒ1.7 eV estimated from linear optical transmittance measurements.Partial financial support was provided by the Spanish Government project TEC2012-37958-C02-01, the Comunidad de Madrid project S2013/MIT-2790, the Universidad de AlcalĂĄ project CCG2014/EXP-051, and the Marie Curie IEF grant âSolarInâ (#331745)
Morphology and arrangement of InN nanocolumns deposited by radio-frequency sputtering: Effect of the buffer layer
We present the structural and optical properties of (0001)-oriented nanocolumnar films of InN deposited on c-sapphire substrates by radio-frequency reactive sputtering. It is observed that the column density and dimensions are highly dependent on the growth parameters of the buffer layer. We investigate four buffer layers consisting of (i) 30 nm of low-growth-rate InN, (ii) 30 nm of AlN deposited on the unbiased substrate (us), (iii) 30 nm of AlN deposited on the reverse-biased substrate (bs), and (iv) a 60-nm-thick bilayer consisting of 30-nm-thick bs-AlN deposited on top of 30-nm-thick us-AlN. Differences in the layer nucleation process due to the buffer layer induce variations of the column density in the range of (2.5-16)Ă109 cm-2, and of the column diameter in the range of 87-176 nm. Best results in terms of mosaicity are obtained using the bs-AlN buffer layer, which leads to a full width at half-maximum of the InN(0002) rocking curve of 1.2°. A residual compressive strain is still present in the nanocolumns. All samples exhibit room temperature photoluminescence emission at âŒ1.6 eV, and an apparent optical band gap at âŒ1.7 eV estimated from linear optical transmittance measurements.Ministerio de EconomĂa y CompetitividadComunidad de MadridUniversidad de AlcalĂĄEuropean Commissio