Effect of rapid thermal annealing on electron emission and DX centers in strained InGaAs/GaAs single quantum well laser diodes

nThermal processing of strained ln(0.2)Ga(0.8)As/GaAs graded-index separate confinement heterostructure single quantum well laser diodes grown by molecular beam epitaxy is investigated. It was found that rapid thermal annealing can improve the 77 K photoluminescence efficiency and electron emission from the active layer, due to removal of nonradiative centers from the InGaAs/GaAs interface. Because of the interdiffusion of Al and Ga atoms, rapid thermal annealing increases simultaneously the density of DX centers in the AlGaAs graded layer. The current stressing experiments of post-growth and annealed laser diodes are indicative of a corresponding increase in the concentration of DX centers, suggesting that DX centers may be responsible for the degradation of laser diode performance.

Effects of annealing time and Si cap layer thickness on the Si/SiGe/Si heterostructures thermal stability

The effects of annealing time and Si cap layer thickness: on the thermal stability of the Si/SiGe/Si heterostructures deposited by disilane and solid-Ge molecule beam epitaxy were investigated. It is found that in the same strain state of the SiGe layers the annealing time decreases with increasing Si cap layer thickness. This effect is analyzed by a force-balance theory and an equation has been obtained to characterize the relation between the annealing time and the Si cap layer thickness. (C) 2001 Elsevier Science B.V. All rights reserved.

In situ annealing treatment and In-doping of GaN epilayers grown by MOVPE

The effects of in situ annealing treatment in the initial growth stage and In-doping during growth of the GaN on the material properties were investigated. GaN was grown by LP-MOVPE. In situ annealing reduced the full-width at half-maximum (FWHM) of X-ray rocking curves and reduced etch pit density of GaN films. It improved the optical properties of the epilayer. Undoped and In-doped GaN films of initial growth stage were investigated. It was found that morphology and optical properties were improved in In-doped samples. (C) 2000 Elsevier Science B.V. All rights reserved.

Strain-induced morphological evolution and preferential interdiffusion in SiGe epitaxial film on Si(100) during high-temperature annealing

Strain relaxation in initially flat SiGe film on Si(1 0 0) during rapid thermal annealing is studied. The surface roughens after high-temperature annealing, which has been attributed to the intrinsic strain in the epilayers. It is interesting to find that high-temperature annealing also results in roughened interface, indicating the occurrence of preferential interdiffusion. It is suggested that the roughening at the surface makes the intrinsic strain in the epilayer as well as the substrate unequally distributed, causing preferential interdiffusion at the SiGe/Si interface during high-temperature annealing. (C) 1999 Elsevier Science B.V. All rights reserved.

An Ameliorated Phase Generated Carrier Demodulation Algorithm With Low Harmonic Distortion and High Stability

A novel ameliorated phase generated carrier (PGC) demodulation algorithm based on arctangent function and differential-self-multiplying (DSM) is proposed in this paper. The harmonic distortion due to nonlinearity and the stability with light intensity disturbance (LID) are investigated both theoretically and experimentally. The nonlinearity of the PGC demodulation algorithm has been analyzed and an analytical expression of the total-harmonic-distortion (THD) has been derived. Experimental results have confirmed the low harmonic distortion of the ameliorated PGC algorithm as expected by the theoretical analysis. Compared with the traditional PGC-arctan and PGC-DCM algorithm, the ameliorated PGC algorithm has a much lower THD as well as a better signal-to-noise-and-distortion (SINAD). A THD of below 0.1% and a SINAD of 60 dB have been achieved with PGC modulation depth (value) ranges from 1.5 to 3.5 rad. The stability performance with LID has also been studied. The ameliorated PGC algorithm has a much higher stability than the PGC-DCM algorithm. It can keep stable operations with LID depth as large as 26.5 dB and LID frequency as high as 1 kHz. The system employing the ameliorated PGC demodulation algorithm has a minimum detectable phase shift of 5 mu rad/root Hz @ 1 kHz, a large dynamic range of 120 dB @ 100 Hz, and a high linearity of better than 99.99%.

missing data imputation: a fuzzy k-means clustering algorithm over sliding window

Tianjin University of Technology

Solving MIN UR problem by triangle evolution algorithm with archiving and niche techniques

In this paper, as an extension of minimum unsatisfied linear relations problem (MIN ULR), the minimum unsatisfied relations (MIN UR) problem is investigated. A triangle evolution algorithm with archiving and niche techniques is proposed for MIN UR problem. Different with algorithms in literature, it solves MIN problem directly, rather than transforming it into many sub-problems. The proposed algorithm is also applicable for the special case of MIN UR, in which it involves some mandatory relations. Numerical results show that the algorithm is effective for MIN UR problem and it outperforms Sadegh's algorithm in sense of the resulted minimum inconsistency number, even though the test problems are linear.