Chemical vapor deposition of anisotropic ultrathin gold films on optical fibers: real-time sensing by tilted fiber Bragg gratings and use of a dielectric pre-coating

Author(s):  
David J. Mandia ◽  
Wenjun Zhou ◽  
Matthew J. Ward ◽  
Howie Joress ◽  
Javier B. Giorgi ◽  
...  
2017 ◽  
Vol 23 (S1) ◽  
pp. 1716-1717 ◽  
Author(s):  
Kimberly Dick Thelander ◽  
L. Reine Wallenberg ◽  
Axel R. Persson ◽  
Marcus Tornberg ◽  
Daniel Jacobsson ◽  
...  

2009 ◽  
Vol 2 ◽  
pp. 035501 ◽  
Author(s):  
Jeonggil Na ◽  
Taesung Kim ◽  
Jae-Boong Choi ◽  
Ju-Young Yun ◽  
Yong-Hyeon Shin ◽  
...  

1995 ◽  
Vol 406 ◽  
Author(s):  
M. S. Gaffneyt ◽  
C. M. Reavesl ◽  
A. L Holmes ◽  
R. S. Smith ◽  
S. P. DenBaars

AbstractMetalorganic chemical vapor deposition (MOCVD) is a process used to manufacture electronic and optoelectronic devices that has traditionally lacked real-time growth monitoring and control. We have developed control strategies that incorporate monitors as real-time control sensors to improve MOCVD growth. An analog control system with an ultrasonic concentration monitor was used to reject bubbler concentration disturbances which exist under normal operation, during the growth of a four-period GaInAs/InP superlattice. Using X-ray diffraction, it was determined that the normally occurring concentration variations led to a wider GaInAs peak in the uncompensated growths as compared to the compensated growths, indicating that closed loop control improved GaInAs composition regulation. In further analysis of the X-ray diffraction curves, superlattice peaks were used as a measure of high crystalline quality. The compensated curve clearly displayed eight orders of satellite peaks, whereas the uncompensated curve shows little evidence of satellite peaks.


1994 ◽  
Vol 363 ◽  
Author(s):  
Paul S. Bowen ◽  
Steve K. Phelps ◽  
Harry I. Ringermacher ◽  
Richard D. Veltri

AbstractThe chemical vapor deposition of silicon nitride can be used to protect advanced materials and composites from high temperature, corrosive, and oxidative environments. Desired coating characteristics, such as uniformity and morphology, cannot be measured in-situ by traditional sensors due to the adverse conditions within the high-temperature reactor. A control strategy has been developed which utilizes a process model and an advanced laser-based sensor to measure the deposition rate of the silicon nitride coating in real-time. The control system is based on a three level hierarchical architecture which functionally separates the process control into PID, supervisory and advanced sensor-based control. Optimal setpoint schedules for the supervisory level are derived from a quasi-fuzzy logic inverse mapping of the process model. An advanced sensor utilizing laser ultrasonics provides real-time coating thickness estimates. Model bias is characterized for each reactor and is correlated on-line with the sensor's deposit thickness estimate. Deviations from model predictions may result in parametric changes to the process model. New setpoint schedules are then created as input to the supervisory control level by regenerating the inverse map of the updated process model.


1993 ◽  
Vol 140 (3) ◽  
pp. 789-796 ◽  
Author(s):  
B. Lecohier ◽  
B. Calpini ◽  
J. ‐M. Philippoz ◽  
H. van den Bergh ◽  
D. Laub ◽  
...  

1990 ◽  
Vol 198 ◽  
Author(s):  
D. E. Aspnes

ABSTRACTA variety of optical methods are now available for studying surface processes and for monitoring layer thicknesses and compositions during semiconductor crystal growth by molecular beam epitaxy (MBE), organometallic chemical vapor deposition (OMCVD), and related techniques. Spectroellipsometry (SE) and spectroreflectometry (SR), the older, primarily bulk-sensitive probes, are now augmented by new, primarily surface-sensitive probes such as reflectance-difference spectroscopy (RDS), second-harmonic generation (SHG), and laser light scattering (LLS). Examples of real-time growth studies now include SE determinations of thicknesses and compositions of AlxGa1–xAs layers on GaAs by organometallic molecular beam epitaxy (OMMBE) to 10 Å thickness scales, RDS determinations of surface dielectric anisotropy spectra of various (001) GaAs surfaces relevant to crystal growth by MBE, and LLS determinations of the evolution of surface roughness during chemical vapor deposition (CVD) growth on Si. Proven capabilities suggest new applications, particularly to growth-interrupted and metastable systems.


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