Structural and surface characterization of large diameter, crystalline AlN substrates for device fabrication

Schujman, Sandra; Schowalter, L. J.; Bondokov, Robert T.; Morgan, Kenneth E.; Liu, Wayne; Smart, J.; Bettles, Tim

doi:10.1016/j.jcrysgro.2007.11.134

Cited by 40 publications

(40 citation statements)

References 14 publications

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“…But when compared to self-nucleated, 28 nominally pure crystals, these obtained FWHM values of E 2 (high) and A 1 (LO) are larger, indicating the considerable defect as well as impurity concentrations in the crystals. There are two additional low-intensity broad bands observed in all the samples at around 480-580 cm 21 and 920-960 cm 21 .…”

mentioning

confidence: 88%

“…Only the phonon modes that are allowed by the selection rules for this symmetry (c-plane AlN) are seen in the spectrum. Their positions are: E 2 (low) mode at 247.7 cm 21 , the E 2 (high) mode at 656.9 cm 21 and the A 1 (LO) mode at 890.9 cm 21 . These peaks are always present in all the crystals and the peak positions closely match with the unstrained, self-nucleated AlN crystal.…”

Section: 22mentioning

confidence: 99%

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Bulk AlN single crystal growth on foreign substrate and preparation of free-standing native seeds

Sumathi

2013

CrystEngComm

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Physical vapour transport growth of aluminium nitride (AlN) single crystals on silicon carbide (SiC) substrates has been optimised and crack-free, large-area, free-standing (0001) AlN wafers were prepared from the grown template crystals. 28 mm diameter single crystals without any polycrystalline surroundings were obtained. Different off-oriented substrates give rise to different growth modes. Sharp and symmetric line shapes of X-ray diffraction (XRD) rocking curves and high intense Raman phonon mode peaks prove high structural quality and homogeneity of the grown crystals. Full width at half maximum of the rocking curves is 72 arcsec for symmetric 00. demonstrates that AlN templates prepared on SiC as a foreign substrate can be used as native seeds for the growth of further homo-epitaxial layers and crystalline boules.

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confidence: 88%

Section: 22mentioning

confidence: 99%

Bulk AlN single crystal growth on foreign substrate and preparation of free-standing native seeds

Sumathi

2013

CrystEngComm

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“…In fact, the growth of an AlN [80] or a low temperature GaN [81][82][83] buffer layer has been intentionally introduced at the initial stage to improve crystal quality. Recently, research regarding GaN epitaxial layers grown on bulk AlN substrates have been reported [84].…”

Section: The Aspect Of Gan Epitaxy Substrate Selectionmentioning

confidence: 99%

CVD solutions for new directions in SiC and GaN epitaxy

Li¹

2015

Linköping Studies in Science and Technology. Dissertations

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This thesis aims to develop a chemical vapor deposition (CVD) process for the new directions in both silicon carbon (SiC) and gallium nitride (GaN) epitaxial growth. The properties of the grown epitaxial layers are investigated in detail in order to have a deep understanding. SiC is a promising wide band gap semiconductor material which could be utilized for fabricating high-power and high-frequency devices. 3C-SiC is the only polytype with a cubic structure and has superior physical properties over other common SiC polytypes, such as high hole/electron mobility and low interface trap density with oxide. Due to lack of commercial native substrates, 3C-SiC is mainly grown on the cheap silicon (Si) substrates. However, there’s a large mismatch in both lattice constants and thermal expansion coefficients leading to a high density of defects in the epitaxial layers. In paper 1, the new CVD solution for growing high quality double-position-boundaries free 3C-SiC using on-axis 4H-SiC substrates is presented. Reproducible growth parameters, including temperature, C/Si ratio, ramp-up condition, Si/H2 ratio, N2 addition and pressure, are covered in this study. GaN is another attractive wide band gap semiconductor for power devices and optoelectronic applications. In the GaN-based transistors, carbon is often exploited to dope the buffer layer to be semi-insulating in order to isolate the device active region from the substrate. The conventional way is to use the carbon atoms on the gallium precursor and control the incorporation by tuning the process parameters, e.g. temperature, pressure. However, there’s a risk of obtaining bad morphology and thickness uniformity if the CVD process is not operated in an optimal condition. In addition, carbon source from the graphite insulation and improper coated graphite susceptor may also contribute to the doping in a CVD reactor, which is very difficult to be controlled in a reproducible way. Therefore, in paper 2, intentional carbon doping of (0001) GaN using six hydrocarbon precursors, i.e. methane (CH4), ethylene (C2H4), acetylene (C2H2), propane (C3H8), iso-butane (i-C4H10) and trimethylamine (N(CH3)3), have been explored. In paper 3, propane is chosen for carbon doping when growing the high electron mobility transistor (HEMT) structure on a quarter of 3-inch 4H-SiC wafer. The quality of epitaxial layer and fabricated devices is evaluated. In paper 4, the behaviour of carbon doping using carbon atoms from the gallium precursor, trimethylgallium (Ga(CH3)3), is explained by thermochemical and quantum chemical modelling and compared with the experimental results. GaN is commonly grown on foreign substrates, such as sapphire (Al2O3), Si and SiC, resulting in high stress and high threading dislocation densities. Hence, bulk GaN substrates are preferred for epitaxy. In paper 5, the morphological, structural and luminescence properties of GaN epitaxial layers grown on N-face free-standing GaN substrates are studied since the N-face GaN has advantageous characteristics compared to the Ga...

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“…high temperature and high growth rate, as well as the deposition of non-polar AlN crystals (Paskova, ) and high electrical resistivity (10 13 Ωcm), AlN is a very expected III-N semiconductor for applications in high power electronics (HEMTs) [3] and optoelectronics (UV LEDs) [4,5]. Despite recent advances in bulk single crystal growth by the seeded sublimation method (PVT) [6][7][8][9], the availability of large size, high quality and high purity material is still lacking to date. In recent papers, we have proposed and validated the high temperature halide chemical vapour deposition (HTCVD) as an alternative route for the deposition of thick (0001) AlN epitaxial layers on Sapphire, SiC and AlN templates [10][11][12][13].…”

mentioning

confidence: 99%

Aluminum nitride homoepitaxial growth on polar and non‐polar AlN PVT substrates by high temperature CVD (HTCVD)

Claudel¹,

Chowanek

Blanquet

et al. 2011

Phys. Status Solidi C

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Due to its wide bandgap (6.2 eV), its high thermal conductivity (3.3 WK‐1cm‐1) and high electrical resistivity (1013 Ωcm), AlN is a very expected III‐N semiconductor for applications in high power electronics (HEMTs) and optoelectronics (UV LEDs). In this work, the homoepitaxial growth of aluminum nitride on polar and non‐polar AlN PVT seeds by HTCVD is studied. From our knowledge, the AlN homoepitaxial growth by HVPE or HTCVD on polar and non‐polar bulk AlN substrates has not been reported. The potential of investigation in this new range of experiments conditions, i.e. high temperature and high growth rate, as well as the deposition of non‐polar AlN crystals (Paskova, Phys. Status Solidi B 245(6), 1011 (2008) and Schwarz and Kneissl, Phys. Status Solidi RRL 1(3), A44 (2007) [1, 2]) is very promising for epitaxial growth and could extend the field of applications (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Structural and surface characterization of large diameter, crystalline AlN substrates for device fabrication

Cited by 40 publications

References 14 publications

Bulk AlN single crystal growth on foreign substrate and preparation of free-standing native seeds

Bulk AlN single crystal growth on foreign substrate and preparation of free-standing native seeds

CVD solutions for new directions in SiC and GaN epitaxy

Aluminum nitride homoepitaxial growth on polar and non‐polar AlN PVT substrates by high temperature CVD (HTCVD)

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