Defect and stress relaxation in HVPE-GaN films using high temperature reactively sputtered AlN buffer

Paskova, T.; Valcheva, E.; Birch, Jens; Tungasmita, Sukkaneste; Persson, Per; Paskov, Plamen; Evtimova, S.; Abrashev, M. V.; Ḿonemar, B.

doi:10.1016/s0022-0248(01)01264-7

Cited by 32 publications

(31 citation statements)

References 5 publications

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“…In addition, the nucleation optimization was of significant importance. Several techniques resulted in significant improvements, such as different single buffers of ZnO [14], [15], metal-organic chemical vapor deposition (MOCVD) grown GaN thin layers [16], [17], reactively sputtered AlN [16], [18], or TiN [19], and also different modifications of growth forced in lateral in-plane directions, as ELOG around masks of different materials and shapes [20]- [22] or grooved substrates. The selection of the nucleation scheme determines the type of HVPE GaN layers usually produced with different thicknesses and different characteristics.…”

Section: A Hydride Vapor Phase Epitaxymentioning

confidence: 99%

“…The development of substrates with both nonpolar and semipolar surfaces was initiated by utilizing foreign substrates, such as (1-102) sapphire or (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) SiC for a-plane GaN, (100) LiAlO 2 or (1-100) SiC for m-plane GaN, and (100) MgAl 2 O 4 for (10-11)-plane GaN, or (110) MgAl 2 O 4 for (10-13)-plane GaN [59]. The HVPE growth of thick layers GaN has also benefited from the ability for self-separation from some of the above substrates [60].…”

Section: Nonpolar and Semipolar Substrate Developmentmentioning

confidence: 99%

“…There are still unresolved questions like In incorporation efficiency in layers grown on GaN substrates with different surface orientations, resulting in different emission wavelength [as in Fig. 6(d) and (e)] in simultaneously grown samples in the [0001], and [11][12][13][14][15][16][17][18][19][20] directions [78], [84], [85] on GaN substrates. Further knowledge gained on this issue as well as a further increase of the substrate size will allow better control of In incorporation for achieving the desired wavelengths.…”

Section: Paskova Et Al: Gan Substrates For Iii-nitride Devicesmentioning

confidence: 99%

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GaN Substrates for III-Nitride Devices

2010

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| Despite the rapid commercialization of III-nitride semiconductor devices for applications in visible and ultraviolet optoelectronics and in high-power and high-frequency electronics, their full potential is limited by two primary obstacles: i) a high defect density and biaxial strain due to the heteroepitaxial growth on foreign substrates, which result in lower performance and shortened device lifetime, and ii) a strong built-in electric field due to spontaneous and piezoelectric polarization in the wurtzite structures along the well-established [0001] growth direction for nitrides. Recent advances in the research, development, and commercial production of native GaN substrates with low defect density and high structural and optical quality have opened opportunities to overcome both of these obstacles and have led to significant progress in the development of several optoelectronic and high-power devices. In this paper, the recent achievements in bulk GaN growth development using different approaches are reviewed; comparison of the bulk materials grown in different directions is made; and the current achievements in device performance utilizing native GaN substrate material are summarized.

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Section: A Hydride Vapor Phase Epitaxymentioning

confidence: 99%

Section: Nonpolar and Semipolar Substrate Developmentmentioning

confidence: 99%

Section: Paskova Et Al: Gan Substrates For Iii-nitride Devicesmentioning

confidence: 99%

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GaN Substrates for III-Nitride Devices

2010

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“…In contrast to metal organic vapour phase epitaxial GaN grown on LT-AlN [1], no highly faulted nucleation zone has been found in HVPE-GaN grown on the HT reactively sputtered AlN [3,4]. It has also been found that the buffer thickness affects the crystal quality and the electrical properties of the HVPE-GaN [3]. However, the determinative physical properties of an optimal buffer are still not well established.…”

mentioning

confidence: 99%

“…Therefore, an AlN film deposited at high temperature (HT), which stipulates the formation of crystalline material, is a good candidate for a buffer layer in the HVPE growth. We have previously reported that HT reactively sputtered AlN is successfully used as buffer for HVPE growth of thick GaN layers on sapphire [3,4]. In contrast to metal organic vapour phase epitaxial GaN grown on LT-AlN [1], no highly faulted nucleation zone has been found in HVPE-GaN grown on the HT reactively sputtered AlN [3,4].…”

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confidence: 99%

Strain Evolution in High Temperature AlN Buffer Layers for HVPE-GaN Growth

Darakchieva

Birch

Paskov

et al. 2002

phys. stat. sol. (a)

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High temperature AlN buffer layers are deposited on a-plane sapphire by reactive magnetron sputtering. The effect of the buffer thickness on the AlN structural properties and surface morphology are studied in correlation with the subsequent hydride vapour phase epitaxy of GaN. A minimum degree of mosaicity and screw dislocation density is determined for a 50 nm thick AlN buffer. With increasing the AlN thickness, a strain relaxation occurs as a result of misfit dislocation generation and higher degree of mosaicity. A blue shift of the E 1 (TO) frequency evaluated by means of infrared reflection spectroscopy is linearly correlated with an increase in biaxial compressive stress in the films through the IR stress factor k b E1 ¼ 2:57 AE 0:26 cm À1 GPa À1 .Introduction To overcome the large lattice mismatch between GaN films and the most commonly used substrates, a number of pre-growth processes including deposition of various buffer layers have been used. It has been shown that in metal organic vapour phase epitaxy the deposition of low temperature (LT) GaN and AlN buffer layers is a key point in order to achieve GaN with desired structural and electronic properties [1,2]. However, the same approach is generally not very successful in hydride vapour phase epitaxy (HVPE). An essential role of buffer layers is to supply nucleation centers with the same orientation as the substrate and to promote lateral growth of GaN by a decrease in interfacial free energy between the film and the substrate. Therefore, an AlN film deposited at high temperature (HT), which stipulates the formation of crystalline material, is a good candidate for a buffer layer in the HVPE growth. We have previously reported that HT reactively sputtered AlN is successfully used as buffer for HVPE growth of thick GaN layers on sapphire [3,4]. In contrast to metal organic vapour phase epitaxial GaN grown on LT-AlN [1], no highly faulted nucleation zone has been found in HVPE-GaN grown on the HT reactively sputtered AlN [3,4]. It has also been found that the buffer thickness affects the crystal quality and the electrical properties of the HVPE-GaN [3]. However, the determinative physical properties of an optimal buffer are still not well established.In this work HT-AlN buffer layers deposited by reactive sputtering on sapphire substrates are investigated. We focus on the influence of the buffer thickness on their structural properties and strain evolution in correlation with the subsequent GaN growth. The strain evolution in the AlN buffers is correlated with their IR vibrational properties.

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Defect Reduction in HVPE Growth of GaN and Related Optical Spectra

Paskova

Paskov

Darakchieva

et al. 2001

phys. stat. sol. (a)

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GaN technology is still based on highly mismatched heteroepitaxial growth on foreign substrates, and therefore needs to overcome a high defect density and a high level of stress in the epitaxial layers. Various attempts have been made to reduce the defects and stress in thick GaN layers. We here report a reduction of the defect density in thick GaN layers grown by hydride vapour phase epitaxy, using regrowth on free-standing GaN films, as well as introducing an AlN buffer and AlN interlayer in the growth sequence. Special focus is put on the optical properties of the material.

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Defect and stress relaxation in HVPE-GaN films using high temperature reactively sputtered AlN buffer

Cited by 32 publications

References 5 publications

GaN Substrates for III-Nitride Devices

GaN Substrates for III-Nitride Devices

Strain Evolution in High Temperature AlN Buffer Layers for HVPE-GaN Growth

Defect Reduction in HVPE Growth of GaN and Related Optical Spectra

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