Deposition and characterization of PECVD phosphorus doped silicon oxynitride layers for integrated optics applications

Phosphorus-doped silicon oxynitride layers have been deposited by a Plasma Enhanced Chemical Vapor Deposition process from $N_20$, 2% $SiH_4/N_2$ and 5% $PH_3/Ar$ gaseous mixtures. The $PH_3/Ar$ flow rate was varied to investigate the effect of the dopant to the layer properties. As deposited and annealed (600, 800, 900 and 1000 °C) layers were characterized by Fourier transform infrared spectroscopy, Rutherford backscattering spectroscopy and spectroscopic ellipsometry. In this way the refractive index could be determined as well as the amount of hydrogen that is responsible for enhanced absorption in the 3rd telecommunication window around 1550 nm. The N-H bonds concentration was found to decrease with the phosphorus concentration. Furthermore the bonded hydrogen in the entire P-doped layers have been eliminated after annealing at 1000 °C, while undoped SiON layers require annealing at 1150 °C

Reduction of hydrogen-induced optical losses of plasma-enhanced chemical vapor deposition silicon oxynitride by phosphorus doping and heat treatment

Plasma enhanced chemical vapor deposition phosphoros-doped silicon oxynitride (SiON) layers with a refractive index of 1.505 were deposited from $N_{2}O$, 2% $SiH_{4}/N_{2}$, and 5% $PH_{3}/Ar$ gaseous mixtures. The $PH_{3}/Ar$ flow rate was varied to investigate the effect of the dopant to the layer properties. We studied the compositions and the chemical environment of phosphorus, silicon, oxygen, nitrogen and hydrogen in these layers by using x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The number of N-H and O-H bonds, which are responsible for optical losses around 1.55 and 1.3 μm, decreases in the as-deposited layers with increasing phosphorus concentration. Furthermore, the bonded hyrogen in all P-doped layers has been eliminated after annealing at a temperature significantly lower than required for undoped silicon oxynitride layers, that is so to say 1000°C instead of 1150°C. The resulting optical loss in the entire third telecommunication window was well below 0.2dB/cm, making P-doped SiON an attractive material for demanding integrated optics applications

Influence of phosphorus doping on hydrogen content and optical losses in PECVD silicon oxynitride

PECVD Phosphorus-doped silicon oxynitride layers (n=1.5) were deposited from N2O, 2%SiH4/N2, NH3 and 5%PH3/Ar gaseous mixtures. Chemical bonds were determined by Fourier transform infrared spectroscopy. N–H bond concentration of the layers decreased from 3.29×10-21 to 0.45×10-21 cm−3, as the 5%PH3/Ar flow rate increased from 0 to 60 sccm. A simultaneous decrease of O–H related bonds was also observed within the same phosphine flow range. The optical loss of slab-type waveguides at λ=1505 nm was found to decrease from 14.1 to 6.2 dB/cm as the 5%PH3/Ar flow rate increased from 0 to 30 sccm, respectively. Moreover, the optical loss values around λ=1400 and 1550 nm were found to decrease from 4.7 to below 0.2 dB/cm and from 1.8 to 1.0 dB/cm respectively. These preliminary results are very promising for applications in low-loss integrated optical devices

Silicon oxynitride based photonics

Silicon oxynitride is a very attractive material for integrated optics. Besides possessing excellent optical properties it can be deposited with refractive indices varying over a wide range by tuning the material composition. In this contribution we will summarize the key properties of this material class and discuss several application examples. Preliminary results on novel processes, which will lead to largely reduced hydrogen incorporation and enable reflow of SiON material, are being presented

B/P Doping in application of silicon oxynitride based integrated optics

In this paper, gaseous precursors containing boron or phosphorous were intentionally introduced in the deposition of SiON layers and upper SiO2 claddings. The measurements show that the as-deposited B/P-doped SiON layers contain less hydrogen than undoped layers. Furthermore, the necessary annealing temperature for elimination of hydrogen related absorption (propagation loss) is greatly reduced in B/P-doped layers

Characterization of thermally treated PECVD SiON layers.

PECVD Silicon Oxynitride (SiON) layers with different refractive indices (1.472-1.635) were grown and characterized. The as-deposited layers have good thickness uniformity (~1%) and a high homogeneity of the refractive index (~ 5x10-4) over the wafer area. For telecommunication application, however, the optical losses of the as-deposited layers are unacceptably high. Therefore, the loss reduction upon annealing as well as the impact of the elevated temperature on the remaining layer properties has been studied. Annealed waveguides with optical losses as low as 0.2 dB/cm at λ = 1550 nm have been realized

Optimization of plasma-enhanced chemical vapor deposition silicon oxynitride layers for integrated optics applications

Silicon oxynitride $(SiO_{x}N_{y}:H)$ layers were grown from 2% $SiH_{4}/N_{2}$ and $N_{2}O$ gas mixtures by plasma-enhanced chemical vapor deposition (PECVD). Layer properties such as refractive index, deposition rate, thickness non-uniformity and hydrogen bond content were correlated to the relevant deposition parameters including radio frequency power, chamber pressure, total gas flow, substrate temperature and $N_{2}O/SiH_{4}$ gas flow ratio. As a result, optimized $SiO_{x}N_{y}:H$ layers could be produced over a wide index range (1.46–1.70) with good thickness uniformity and sufficiently high deposition rate. With a refraction index non-uniformity < 5 × $10^{− 4}$ a thickness non-uniformity could be obtained below 1% over a 70 × 70 mm2 area of a 100 mm wafer at a deposition rate > 50 nm/min. The material composition and the optical properties of the $SiO_{x}N_{y}:H$ layers were characterized by spectroscopic ellipsometry, X-ray Photoelectron Spectroscopy, Fourier Transform Infrared spectroscopy and prism coupler techniques. A simple atomic valence model is found to describe the measured atomic concentrations for PECVD silicon oxynitride layers. \ud \u

American Society of Anesthesiologists Physical Status Classification System: History, Development, Reliability, and Its Future

The American Society of Anesthesiologists Physical Status (ASA PS) classification has long been used as a ranking system that quantifies patient health before anaesthesia and surgery. When initially developed, the ASA PS intended application was purely statistical. However, nowadays it is commonly used by surgical specialties to determine a patient’s likelihood of developing postoperative complications, despite studies reporting scoring method subjectivity and inconsistencies among anaesthesiologists in assigning these scores. Over the years, the ASA PS classifications have undergone many changes and modifications to address its limitations. There are a few points to be discussed if all shortcomings are to be treated and interobserver variability is to be limited

The effects of irrigation water salinity, potassium nitrate fertilization, proline spraying and leaching fraction on the growth and chemical composition of corn grown in calcareous soil

Two pot experiments were conducted to study the effect of irrigation with saline water in relation to KNO3 fertilization, proline spraying and leaching fraction on the growth and Na+, K+, Cl-, NO3 - and proline contents of corn (Zea mays L.) plant grown on a nonsaline calcareous soil. The treatments included irrigation waters of different salinity (0.54, 3.36, 5.88 or 7.95 dS/m), three rates of KNO3 (0, 4 and 8 g/pot) fertilizer and foliar application with three rates of proline (0, 100 and 200 mg/L). The first experiment was irrigated with the water to the field capacity with leaching fraction and the second without leaching fraction. The experimental design was a split split plot with three replications. Also, the effect of these parameters on salt accumulation in soil was discussed. The obtained results showed that the dry weight of shoots was decreased as salinity of irrigation water increased. The highest decreases were attained with waters of 5.88 and 7.95 dS/m as compared with dry weight due to irrigation with 0.54 or 3.36 dS/m water salinity. High salinity of water increased the shoot contents of Na+, Cl-, proline and decreased NO3 - contents with or without leaching fraction, but the values without leaching fraction were higher than those of without leaching fraction. Also, increasing the salinity of irrigation water decreased K content in shoot which was higher with leaching than without leaching. On the other hand, KNO3 fertilization or proline spraying decreased Na+, Cl- contents and increased K+ or NO3 - contents in plant shoot and their values without leaching were higher than with leaching. The EC values of soil were increased with both increasing salinity of irrigation water and KNO3 fertilization. The decreased plant growth due to water salinity was partially offset by KNO3 fertilization, proline spraying and leaching fraction application. Also, KNO3 fertilization was more effective than proline for reducing the adverse effect of water salinity

Study of 9Be+12C elastic scattering at energies near the Coulomb barrier

In this work, angular distribution measurements for the elastic channel were performed for the 9Be+12C reaction at the energies ELab=13.0, 14.5, 17.3, 19.0 and 21.0 MeV, near the Coulomb barrier. The data have been analyzed in the framework of the double folding S\~ao Paulo potential. The experimental elastic scattering angular distributions were well described by the optical potential at forward angles for all measured energies. However, for the three highest energies, an enhancement was observed for intermediate and backward angles. This can be explained by the elastic transfer mechanism. Keywords: 9Be+12C, Elastic Scattering, S\~aoo Paulo Potential