Real‐time control of molecular beam epitaxy by optical‐based flux monitoring

1993 ◽  
Vol 63 (23) ◽  
pp. 3131-3133 ◽  
Author(s):  
S. A. Chalmers ◽  
K. P. Killeen
Keyword(s):  
Molecular Beam Epitaxy ◽  
Real Time ◽  
Molecular Beam ◽  
Real Time Control ◽  
Time Control ◽  
Flux Monitoring

Optical-based Flux Monitoring of Atomic Antimony Sources for Molecular Beam Epitaxy

1995 ◽  
Vol 406 ◽  
Author(s):  
P. D. Brewer ◽  
K. P. Killeen
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Flux Measurement ◽  
Product Distribution ◽  
Effusion Cell ◽  
Real Time Control ◽  
Double Pass ◽  
Mbe Growth ◽  
Time Control ◽  
Flux Monitoring

AbstractIn this paper we discuss the use of optical-based flux monitoring (OFM) for real-time control of atomic antimony fluxes for applications in molecular beam epitaxy. Atomic antimony beams were generated using a two-zone cracking effusion cell. The product distribution of the source was characterized using a time-of-flight mass spectrometer employing resonance-enhanced laser ionization. A double-pass OFM system has been developed to monitor the atomic antimony beam that is capable of precise flux measurement during MBE growth.

Real Time Control of III-V Semiconductor Surfaces During Movpe Growth by Reflectance Anisotropy Spectroscopy

1993 ◽  
Vol 334 ◽  
Author(s):  
K. Ploska ◽  
W. Richter ◽  
F. Reinhardt ◽  
J. JÖnsson ◽  
J. Rumberg ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Real Time ◽  
Molecular Beam ◽  
Substrate Surface ◽  
Exchange Reactions ◽  
Real Time Control ◽  
Time Resolved ◽  
Reflectance Anisotropy ◽  
Time Control ◽  
Metalorganic Molecular Beam Epitaxy

AbstractReflectance anisotropy spectroscopy (RAS) is presented as real time analytical tool for metalorganic vapourphase epitaxy (MOVPE) of III-V-semiconductors. This optical method derives its surface sensitivity from the anisotropy of surface structures. It is shown that it is possible to monitor with RAS the oxide desorption from the substrate and that the substrate surface conditions thereafter, still in the pregrowth stage, can be correlated with certain reconstructions of the (001)-surfaces of InP and GaAs. The latter is possible through simultaneous RAS and RHEED measurements during MBE (molecular beam epitaxy) or MOMBE (metalorganic molecular beam epitaxy). Characteristic spectral features are also observed for other binary or ternary III-V-semiconductors. Time resolved measurements during growth give monolayer resolution for the growth rate in the case of GaAs. In the study of heterointerface growth exchange reactions between As and P together with their corresponding reaction time constants can be monitored and conclusions for the epitaxial growth procedure can be drawn.

A Real Time Control Architecture for Continuously Managing Patients in a Care Unit

1995 ◽  
Vol 34 (05) ◽  
pp. 475-488
Author(s):  
B. Seroussi ◽  
J. F. Boisvieux ◽  
V. Morice
Keyword(s):  
Real Time ◽  
Linear Time ◽  
Treatment Plan ◽  
Control Architecture ◽  
Real Time Control ◽  
Time Representation ◽  
Time Control ◽  
Continuous Support ◽  
Definition Of ◽  
Computerized System

Abstract:The monitoring and treatment of patients in a care unit is a complex task in which even the most experienced clinicians can make errors. A hemato-oncology department in which patients undergo chemotherapy asked for a computerized system able to provide intelligent and continuous support in this task. One issue in building such a system is the definition of a control architecture able to manage, in real time, a treatment plan containing prescriptions and protocols in which temporal constraints are expressed in various ways, that is, which supervises the treatment, including controlling the timely execution of prescriptions and suggesting modifications to the plan according to the patient’s evolving condition. The system to solve these issues, called SEPIA, has to manage the dynamic, processes involved in patient care. Its role is to generate, in real time, commands for the patient’s care (execution of tests, administration of drugs) from a plan, and to monitor the patient’s state so that it may propose actions updating the plan. The necessity of an explicit time representation is shown. We propose using a linear time structure towards the past, with precise and absolute dates, open towards the future, and with imprecise and relative dates. Temporal relative scales are introduced to facilitate knowledge representation and access.

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