Structural and electrical properties of reactively sputtered InN thin films on AlN-buffered (00.1) sapphire substrates: Dependence on buffer and film growth temperatures and thicknesses

Kistenmacher, Thomas J.; Ecelberger, S. A.; Bryden, Wayne A.

doi:10.1063/1.354822

Cited by 32 publications

(8 citation statements)

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“…It is known that usually the insertion of an AlN buffer layer leads to an improvement of the subsequent III-nitride crystalline quality, which is valid also for RF reactive sputtering technique [18][19][20][21]. It has also been reported that biasing the substrate can lead to an improvement of the structural quality of RF-sputtered AlN through an increase in the kinetic energy of the impinging ions [22].…”

Section: Introductionmentioning

confidence: 86%

Morphology and arrangement of InN nanocolumns deposited by radio-frequency sputtering: Effect of the buffer layer

Monteagudo-Lerma

Valdueza-Felip

Núñez-Cascajero

et al. 2016

Journal of Crystal Growth

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a b s t r a c tWe 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) Â 10 9 cm À 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 $ 1.6 eV, and an apparent optical band gap at $ 1.7 eV estimated from linear optical transmittance measurements.

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Section: Introductionmentioning

confidence: 86%

Morphology and arrangement of InN nanocolumns deposited by radio-frequency sputtering: Effect of the buffer layer

Monteagudo-Lerma

Valdueza-Felip

Núñez-Cascajero

et al. 2016

Journal of Crystal Growth

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“…This can be understood by the fact that the grain size obtained in thick AlN layers deposited using the same conditions as the buffer layer is~40 nm, significantly larger than the buffer layer thickness. Thus a non-homogeneous surface coverage can be expected in a three dimensional growth model [26]. The increase of the buffer layer thickness to 30 nm enables the total suppression of the interface damage (no diffraction peak at 2θ~35°) and leads to a reduction of the FWHM of the AlN(0002) reflection peak to 1.63°, to be compared to FWHM = 1.91°for the optimized unbiased layer (see …”

Section: Two-step Deposition Methodsmentioning

confidence: 99%

Two-step method for the deposition of AlN by radio frequency sputtering

et al. 2013

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This paper presents a detailed study of the influence of deposition conditions on structural and morphological properties of AlN thin films synthesized on c-sapphire substrates by radio frequency (RF) reactive sputtering. After the optimization of deposition parameters such as RF power and substrate temperature, the substrate bias has been identified as a critical variable to improve the structural properties of the AlN layers. The use of negative bias leads to a decrease of the full-width at half-maximum (FWHM) of the rocking curve of the AlN(0002) x-ray reflection and an increase of the grain size. However, 2θ/ω x-ray scans of layers grown under negative bias reveal lattice disorder at the AlN/sapphire interface, which is attributed to the highly accelerated positive ions (Al + , N + , N 2 + ) arriving to the substrate at the initial stages of the deposition process. In order to prevent this interface degradation, we propose a twostep deposition method which consists of starting the growth with an unbiased AlN buffer layer, at least 30 nm thick, followed by AlN deposition under negative bias. This procedure results in high-quality AlN layers with FWHM of the rocking curve of the (0002) reflection of 1.63°, grain size of~40 nm and root-mean-square surface roughness of 0.4 nm.

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“…The behavior of pure InN growth might help to shed light on the mechanism of the formation of high concentration of InN in the ternary. InN has been prepared by various techniques [6][7][8][9][10][11][12][13]. However, InN normally shows poor optical properties, a high background carrier concentration and poor crystalline properties with indium clusters found from the x-ray diffraction spectrum.…”

Section: Introductionmentioning

confidence: 99%