A new system for sodium flux growth of bulk GaN. Part II: in situ investigation of growth processes
Online Publication Date2016-09-09
Print Publication Date2016-12
Permanent link to this recordhttp://hdl.handle.net/10754/623508
MetadataShow full item record
AbstractWe report recent results of bulk GaN crystal growth using the sodium flux method in a new crucible-free growth system. We observed a (0001) Ga face (+c-plane) growth rate >50 µm/h for growth at a N2 overpressure of ~5 MPa and 860 °C, which is the highest crystal growth rate reported for this technique to date. Omega X-ray rocking curve (ω-XRC) measurements indicated the presence of multiple grains, though full width at half maximum (FWHM) values for individual peaks were <100 arcseconds. Oxygen impurity concentrations as measured by secondary ion mass spectroscopy (SIMS) were >1020 atoms/cm3. By monitoring the nitrogen pressure decay over the course of the crystal growth, we developed an in situ method that correlates gas phase changes with precipitation of GaN from the sodium-gallium melt. Based on this analysis, the growth rate may have actually been as high as 90 µm/h, as it would suggest GaN growth ceased prior to the end of the run. We also observed gas phase behavior identified as likely characteristic of GaN polynucleation.
CitationVon Dollen P, Pimputkar S, Alreesh MA, Nakamura S, Speck JS (2016) A new system for sodium flux growth of bulk GaN. Part II: in situ investigation of growth processes. Journal of Crystal Growth 456: 67–72. Available: http://dx.doi.org/10.1016/j.jcrysgro.2016.08.018.
SponsorsThanks to Guy Patterson and Doug Rehn for help with many aspects of equipment design and fabrication. Thanks to Dr. Tom Mates for performing the SIMS measurements and to Steven Griffiths and Thomas Malkowski for many helpful conversations and insights. The authors acknowledge the support from the Solid State Lighting and Display/Energy Center at, University of California, Santa Barbara and the Materials Research Laboratory (MRL) Central Facilities, which are supported by the MRSEC Program of the NSF under Award no. DMR 1121053; a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org). This work was supported by the KACST-KAUST-UCSB Solid State Lighting Program.
JournalJournal of Crystal Growth
CollectionsPublications Acknowledging KAUST Support
Showing items related by title, author, creator and subject.
Epitaxial Growth of Two-Dimensional Layered Transition-Metal Dichalcogenides: Growth Mechanism, Controllability, and ScalabilityLi, Henan; Li, Ying; Aljarb, Areej; Shi, Yumeng; Li, Lain-Jong (Chemical Reviews, American Chemical Society (ACS), 2017-07-06) [Article]Recently there have been many research breakthroughs in two-dimensional (2D) materials including graphene, boron nitride (h-BN), black phosphors (BPs), and transition-metal dichalcogenides (TMDCs). The unique electrical, optical, and thermal properties in 2D materials are associated with their strictly defined low dimensionalities. These materials provide a wide range of basic building blocks for next-generation electronics. The chemical vapor deposition (CVD) technique has shown great promise to generate high-quality TMDC layers with scalable size, controllable thickness, and excellent electronic properties suitable for both technological applications and fundamental sciences. The capability to precisely engineer 2D materials by chemical approaches has also given rise to fascinating new physics, which could lead to exciting new applications. In this Review, we introduce the latest development of TMDC synthesis by CVD approaches and provide further insight for the controllable and reliable synthesis of atomically thin TMDCs. Understanding of the vapor-phase growth mechanism of 2D TMDCs could benefit the formation of complicated heterostructures and novel artificial 2D lattices.
Growth increments of the recent brachiopod Magellania venosa mechanically marked in Paso Comau and Comau Fjord, Chile, 2011/2012, supplement to: Baumgarten, Sebastian; Laudien, Jürgen; Jantzen, Carin; Häussermann, Verena; Försterra, Günter (2013): Population structure, growth and production of a recent brachiopod from the Chilean fjord region. Marine Ecology, 35(4), 401-413Baumgarten, Sebastian; Laudien, Jürgen; Jantzen, Carin; Häussermann, Verena; Försterra, Günter (PANGAEA - Data Publisher for Earth & Environmental Science, 2015) [Dataset]Magellania venosa, the largest recent brachiopod, occurs in clusters and banks in population densities of up to 416 ind/m**2 in Comau Fjord, Northern Chilean fjord region. Below 15 m, it co-occurs with the mytilid Aulacomya atra and it dominates the benthic community below 20 m. To determine the question of why M. venosa is a successful competitor, the in situ growth rate of the brachiopod was studied and its overall growth performance compared with that of other brachiopods and mussels. The growth in length was measured between February 2011 and March 2012 after mechanical tagging and calcein staining. Settlement and juvenile growth were determined from recruitment tiles installed in 2009 and from subsequent photocensus. Growth of M. venosa is best described by the general von Bertalanffy growth function, with a maximum shell length (Linf) of 71.53 mm and a Brody growth constant (K) of 0.336/year. The overall growth performance (OGP index = 5.1) is the highest recorded for a rynchonelliform brachiopod and in the range of that for Mytilus chilensis (4.8-5.27), but lower than that of A. atra (5.74). The maximal individual production (PInd) is 0.29 g AFDM/ind/year at 42 mm shell length and annual production ranges from 1.28 to 89.25 g AFDM/year/m**2 (1-57% of that of A. atra in the respective fjords). The high shell growth rate of M. venosa, together with its high overall growth performance may explain the locally high population density of this brachiopod in Comau Fjord. However, the production per biomass of the population (P/B-ratio) is low (0.535) and M. venosa may play only a minor role in the food chain. Settling dynamics indicates that M. venosa is a pioneer species with low juvenile mortality. The coexistence of the brachiopod and bivalve suggests that brachiopod survival is affected by neither the presence of potential brachiopod predators nor that of space competitors (i.e. mytilids).
Dataset on the specific growth rate of seaweed growing in experimental and aquaculture conditions at various biomass densities, irradiation and nutrient concentrations, supplement to: Xiao, Xi; Agustí, Susana; Lin, Fang; Xu, Caicai; Yu, Yan; Pan, Yaoru; Li, Ke; Wu, Jiaping; Duarte, Carlos Manuel (2019): Resource (Light and Nitrogen) and Density-Dependence of Seaweed Growth. Frontiers in Marine Science, 6Xiao, Xi; Agusti, Susana; Lin, Fang; Xu, Caicai; Yu, Yan; Pan, Yaoru; Li, Ke; Wu, Jiaping; Duarte, Carlos M. (PANGAEA - Data Publisher for Earth & Environmental Science, 2019) [Dataset]We searched the published literature for data on the density-dependence of seaweed growth under different nutrient levels. The search was based on the Web of Science®, accessed in May 2019, using a combination of keywords including "seaweed & remediation", "seaweed & bioremediation", "seaweed & nitrogen removal" and "seaweed & phosphorous removal". These searches yielded a total of 164 papers reporting growth rates and biomass density for seaweed. We retrieved the growth rates, biomass density, concentration of the dominant forms of inorganic nutrients - ammonia, nitrate and phosphate - and incident irradiance, and recorded the taxa (chlorophyta, phaeophyta or rhodophyta). This generated a raw dataset containing a total of 1729 experimental assessments. For all the assessments, we further converted all growth rates to units of % day-1 and biomass density (i.e. the seaweed biomass per unit habitat volume) to g FW L-1.