Development of GaN wafers via the ammonothermal method

Letts, Edward; Hashimoto, Tadao; Hoff, Sierra; Key, Daryl; Male, Keith B.; Michaels, Mathew

doi:10.1016/j.jcrysgro.2014.06.004

Cited by 19 publications

(23 citation statements)

References 9 publications

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“…21 The internal absorption has been found to be significant in nitrides for emission energy below the GaN band-edge due to background doping, leading to an increase in electronic transitions between donor-acceptor levels and structural defects. [59][60][61] For example, the absorption coefficient at 450 nm of Bulk-GaN substrates has been found to increase with increasing unintentional O-impurity concentration. 60,61 The internal absorption in the 6-lm-thick PSS-GaN substrate in comparison with the 300-lm-thick Bulk-GaN substrate might be higher due to the higher O-impurity concentration of about 1.…”

Section: Discussionmentioning

confidence: 99%

Role of substrate quality on the performance of semipolar (112¯2) InGaN light-emitting diodes

Dinh

Corbett

Parbrook

et al. 2016

Journal of Applied Physics

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We compare the optical properties and device performance of unpackaged InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) emitting at ∼430 nm grown simultaneously on a high-cost small-size bulk semipolar (112¯2) GaN substrate (Bulk-GaN) and a low-cost large-size (112¯2) GaN template created on patterned (101¯2) r-plane sapphire substrate (PSS-GaN). The Bulk-GaN substrate has the threading dislocation density (TDD) of ∼105 cm−2–106 cm−2 and basal-plane stacking fault (BSF) density of 0 cm−1, while the PSS-GaN substrate has the TDD of ∼2 × 108 cm−2 and BSF density of ∼1 × 103 cm−1. Despite an enhanced light extraction efficiency, the LED grown on PSS-GaN has two-times lower internal quantum efficiency than the LED grown on Bulk-GaN as determined by photoluminescence measurements. The LED grown on PSS-GaN substrate also has about two-times lower output power compared to the LED grown on Bulk-GaN substrate. This lower output power was attributed to the higher TDD and BSF density.

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Section: Discussionmentioning

confidence: 99%

Role of substrate quality on the performance of semipolar (112¯2) InGaN light-emitting diodes

Dinh

Corbett

Parbrook

et al. 2016

Journal of Applied Physics

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“…For instance, while only 0.119g of Ga is required per unit of PV cell, 226g of Si would be required for the same unit [15]. This implies that, the role of element gallium in the electrical and electronic devices is a specialised one; therefore there appears to be trade-offs between the criticality and substitutability which should be considered [12], such that neither the efficiency nor the performance of a destined product is seriously affected.…”

Section: Substitution By Other Non-critical Elementsmentioning

confidence: 99%

“…These applications command high quality [7], as such, impurities are relatively Licensed Under Creative Commons Attribution CC BY low and are likely to be from production methods used. Some reported impurities include oxygen, zinc, tellurium and sulphur [12][13][14] in the purity of over 99.9%. Total gallium concentration in LED devices ranges from 0.001 to 0.005 g/unit [1,15].…”

Section: Introductionmentioning

confidence: 99%

“…Production of gallium arsenide is 30% efficient and 70% is captured for recycling and the capturing is only 71% efficient. Since the current technology does not allow extraction of gallium on its own [12], therefore, decline in production of one or more host elements can seriously affect its production [3,6,7]. This loss, besides the loss in primary production could add more to the criticality of the element.…”

Section: Introductionmentioning

confidence: 99%

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The Growing Global Demand for Element Gallium: Electrical and Electronic Waste and Coal Fly Ash as Alternative Sources for its Sustainable Supply

2017

IJSR

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Gallium (Ga) is listed among the critical elements because of its high demand, low crustal concentration and dispersed occurrence. Growth in demand for this element is a response to proliferation in production of electronic devices and a global effort to decarbonised power production. This situation calls for exploitation of alternative sources such as fly ash and recycling processes from finished products. Wide implementation of these options is yet to be witnessed or still in their infancy with only a few facilities worldwide. This is attributable to low material intensity per unit product and the fact that this kind of waste has not accumulated high enough to attract recycling for instance. Most gallium bearing devices though have other critical, precious and or non-precious elements that co-exist with it. These co-existing elements are relatively high in concentrations and some of them are already being recycled from the same end-of-life products. Therefore an option that involves co-recovery of gallium together with other co-existing elements which are already being recycled and extraction from other sources such as fly ash is to be a viable pursuit in sustaining gallium supply. Viability stems on the similarities of gallium concentration in those sources, recovery methods and conditions used in recycling of gallium. More research however, to explore potential combinations of co-existing metals to be co-extracted with and methods to be employed is vital.

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“…From that knowledge, we can control the defect concentration in order to optimize and improve the devices performance. The defects are often dependent on growth technique, e.g., ammonothermal grown GaN has low concentration of structural defects when compare to others but high concentration of impurities, see [44]. There are a lot of studies on defects in GaN grown by other techniques such as MOCVD [45]- [47], MBE [48], [49] and HVPE [50]- [52].…”

Section: Introductionmentioning

confidence: 99%

Investigation of deep levels in bulk GaN

Duc¹

2014

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The first gallium nitride (GaN) crystal was grown by hydride vapor phase epitaxy in 1969 by Maruska and Tietjen and since then, there has been an intensive development of the field, especially after the ground breaking discoveries concerning growth and p-type doping of GaN done by the 2014 year Nobel Laureates in Physics, Isamu Akasaki, Hiroshi Amano and Shuji Nakamura. GaN and its alloys with In and Al belong to a semiconductor group which is referred as the III-nitrides. It has outstanding properties such as a direct wide bandgap (3.4 eV for GaN), high breakdown voltage and high electron mobility. With these properties, GaN is a promising material for a variety of applications in electronics and optoelectronics. The perhaps most important application is GaN-based light-emitting-diodes (LED) which can produce a highbrightness blue light. Since the bandgap of GaN can be controlled by alloying it with aluminium (Al) or indium (In) for a larger or smaller bandgap, respectively, GaN is very important for optoelectronic applications from infrared to the deep ultraviolet region. There are other semiconductors with bandgap similar to GaN such as SiC, and the first commercially blue light emitting LEDs where manufactured in SiC, however, SiC has an indirect bandgap with a low efficiency of emitting photons, and today, the SiC based LEDs have been completely replaced by the considerable more efficient GaN based LEDs. One problem, which has hampered the development of GaN based devices, is the lack of native substrate of GaN. Due to that, most of the GaN based devices are fabricated on foreign substrates such as SiC or Al2O3. Growing on a foreign substrate results in high threading dislocation (TD) densities (~109 cm-2) and stress in the GaN layer due to lattice mismatch and difference of thermal expansion coefficient between GaN and the substrate. The high TD density and the stress influence the performance of the devices. Another important aspect related to GaN which has attracted manystudies is how defects affect the efficiency of GaN-based devices.Therefore, it is necessary to understand the properties and to identifythem. When we know there properties, one can estimate how they willinfluence the behavior of devices, and thereby, optimize the performance of the device for its application. Basically, a fundamental knowledge of defect properties, and how to introduce them in a controlled manner, or to avoid them, is important in order to optimize the performance of devices. Defects can be introduced both intentionally and unintentionally into semiconductors during the growth process, during processing of the device or from the working environment, for example, devices working in a radioactive ambient are more likely to have defects induced by irradiation. This thesis is focused on electrical characterization of defects in bulk GaN grown by halide vapor phase epitaxy (HVPE) by using deep level transient spectroscopy. Other measurement techniques like currentvoltage measurement (IV), capacitance-voltage measurement (CV) a...

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Development of GaN wafers via the ammonothermal method

Cited by 19 publications

References 9 publications

Role of substrate quality on the performance of semipolar (112¯2) InGaN light-emitting diodes

Role of substrate quality on the performance of semipolar (112¯2) InGaN light-emitting diodes

The Growing Global Demand for Element Gallium: Electrical and Electronic Waste and Coal Fly Ash as Alternative Sources for its Sustainable Supply

Investigation of deep levels in bulk GaN

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