The growth of GaN on lithium gallate (LiGaO2) substrates for material integration

Compliant substrates offer a new approach for strain management in semiconductors. Various implementations and processes for achieving substrate compliancy have been proposed and demonstrated. These include the use of twist-, glass-, and metal-bonds. A recent focus in our work has been on the growth of GaN on a novel and easily removable substrate—lithium gallate—for the ultimate regrowth on a bonded GaN template. The bonding technology is important to reduce thermal stresses during the regrowth step. Herein, we focus on the understanding of the growth of GaN on lithium gallate.     

N-order direct form digital filters with integer arithmetic

For direct form digital filters with integer arithmetic, a characterization of the initial condition vector and state vectorX(), for a fixed, > 1, is established without the intermediate state vectors. This is used to determine initial conditions for stability and initial conditions for convergence to a limit cycle. Also, several properties of limit cycles are proven.     

Plasma Lipid Peroxidation and Vitamin E Supplementation during High Intakes of Fish-Oil Fatty Acids

High intakes of fish oil concentrates (15g/day MaxEPA) resulted in increased TBARS in plasma after 2 weeks irrespective of the vitamin E intake and plasma content. After 4 weeks TBARS values returned to normal despite continued MaxEPA supplementation and different vitamin E levels. Fish oil supplements resulted in increased whole-blood aggregation and higher plasma glucose concentrations which did not occur when extra vitamin E was given. No significant differences in plasma cholesterol levels were observed.     

Effects of higher order nonlinearities on second-order frequency mixing

Equations are presented here which describe second-order nonlinear frequency mixing under conditions where third-order non-linearities significantly alter the phase-matching relations. The coupled amplitude and phase equations illustrate that additional phase mismatch of the second-order process can be expected due to third-order nonlinearities. These nonlinearities include refractive index changes for a wave at one frequency due to waves at other frequencies. Growth of off-axis weak waves (small scale self-focusing) is described in terms of four-wave mixing in the presence of the second-order frequency mixing. It is shown that in at least some cases growth of off-axis waves is enhanced by second-order frequency mixing.     

CROSS-FLOW FILTRATION OF FUNGAL SUSPENSION WITH REVERSED-FLOW CLEANING

The separation of fungal suspension Trichoderma reesei was studied by using cross-flow filtration(CFF)with re-versed-flow cleaning(RFC)technique.The advantage of this technique is demonstrated in comparison with other filtra-tion techniques.The filtration rate is influenced by different frequencies of RFC.For optimum combination of CFF andRFC,both experimental and theoretical considerations are necessary and are discussed.An expression has been derivedfor the optimum filtration time needed to maximize the flux for a given RFC period assuming that the filtration stage canbe approximated by Ruth’s equation.The practical usefulness of this calculation is demonstrated on a batch thickening op-eration.     

Spectral Radiance Estimates of Leaf Area and Leaf Phytomass of Small Grains and Native Vegetation

Similarities and/or dissimilarities in radiance characteristics were studied among barley (Hordeum vulgare L.), oats (Avena fatua L.), spring and winter wheat (Triticum aestivum L.), and shortgrass prairie vegetation. The site was a Williams loam soil (fine-loamy mixed, Typic Argiborolls) near Sidney, Montana. Radiances were measured with a truck-mounted radiometer. The radiometer was equipped with four wavelength bands: 0.45 to 0.52, 0.52 to 0.60, 0.63 to 0.69, and 0.76 to 0.90 , ?m. Airborne scanner measurements were made at an altitude of 600 m four times during the season under clear sky conditions. The airborne scanner was equipped with the same four bands as the truck-mounted radiometer plus the following: 1.00 to 1.30, 1.55 to 1.75, 2.08 to 2.35, and 10.4 to 12.5 ?m. Comparisons using individual wave bands, the near IR/red ((0.76 to 0.90 ?m)/(0.63 to 0.69 ?m)) ratio and the normalized difference vegetation index (ND=(IR-red)/(IR+red)) showed that only only during limited times during the growing season were some of the small grains distinguishable from one another and from native rangeland vegetation. There was a common relation for all small grains between leaf area index and green leaf phytomass and between leaf area index or green leaf phytomass and the IR/red ratio.     

Dermatitis-inducing furanocoumarins on leaf surfaces of eight species of Rutaceous and Umbelliferous plants

Eight species of Rutaceae or Umbelliferae, known to cause or suspected of causing photophytodermatitis, had the linear furanocoumarins psoralen, bergapten, and xanthotoxin on their leaf surfaces, in concentrations varying from 0.014 to 1800 /gmg/g fresh weight, equivalent to 0.17–56% of the total leaf concentration. The higher percentage generally observed for spring leaves compared to autumn leaves suggests a higher rate of transfer of these furanocoumarins to the surface in the younger leaves. Among the plants studied,Ruta graveolens had the highest surface concentrations of all three furanocoumarins. The relatively high effectiveness in causing dermatitis of some species with low surface concentrations may be explained by a more effective mechanism of transfer of the furanocoumarins to the skin. A role in the defense of the plant is suggested by their accumulation on the plant surface.A paper based on the work reported here was presented at the Groupe Polyphénols conference, Brock University, St. Catharines, Ontario, Canada, August 19–19, 1988.     

The behavior of unintentional impurities in Ga0.47 In0.53As grown by MBE

A number of factors contribute to the high n-type background carrier concentration (high 10¹⁵ to low 10¹⁶ cm⁻³) measured in MBE Ga_0.47In_0.53As lattice-matched to InP. The results of this study indicate that the outdiffusion of impurities from InP substrates into GalnAs epitaxial layers can account for as much as two-thirds of the background carrier concentration and can reduce mobilities by as much as 40%. These impurities and/or defects can be gettered at the surfaces of the InP by heat treatment and then removed by polishing. The GalnAs epitaxial layers grown on the heat-treated substrates have significantly improved electrical properties. Hall and SIMS measurements indicate that both donors and acceptors outdiffuse into the epitaxial layers during growth resulting in heavily compensated layers with reduced mobilities. The dominant donor species was identified by SIMS as Si, and the dominant acceptors as Fe, Cr and Mn.     

The monos memory transitor: Application in a radiation-hard nonvolatile RAM

The MONOS (metal-oxide-nitride-oxide-silicon) device is a prime candidate for use as the nonvolatile memory element in a radiation-hardened RAM (random-access memory). The endurance, retention and radiation properties of MONOS memory transistors have been studied as a function of post nitride deposition annealing. Following the nitride layer deposition, all devices were subjected to 800°C oxidation step and some were then annealed at 900°C in nitrogen. The nitrogen anneal produces an increase in memory window size of approximately 40%. The memory window center of the annealed devices is shifted toward more positive voltages and is more stable with endurance cycling. Endurance cycling to 10⁹ cycles produces a 20% increase in memory window size and a 60% increase in decay rate. For a radiation total dose of 10⁶ rads (Si), the memory window size is essentially unchanged and the decay rate increases approximately 13%. A combination of 10⁹ cycles and 10⁶ rads (Si) reduces the decades of retention (in sec) from 6.3 to 4.3 for a ±23-V 16-μsec write/erase pulse.