Effect of layer thickness variations on propagation delay and penetration depth of a quarter-wave distributed Bragg reflector

30-pair AlAs/GaAs distributed Bragg reflector (DBR), which has 1030 nm center reflectivity, is studied extensively by means of High Resolution X-ray Diffraction (HR-XRD) and reflectivity measurements. Theta/2-Theta measurements and dynamical simulations have been done for (002), (004) and (006) planes to determine strain and thickness of AlAs and GaAs layers in the DBR stack. Reciprocal space mappings (RSMs) are measured for same planes and also for (224) plane to find out tilt and relaxation of the DBR stack. Relaxation is not observed and it is confirmed with symmetric in-plane (400) Theta/2-Theta and RSM measurements. This is a first study in the literature according to the best of our knowledge. Finally, we have shown sensitivity of high angle diffraction planes to disorders in crystal. Angle-dependent reflectivity simulations have been also done and compared with measurements. 99.99% reflectivity is obtained with 99.5 nm stop bandwidth and 482.7 nm penetration depth.

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Absorption loss influence on optical characteristics of multilayer distributed Bragg reflector: wavelength-scale analysis by the method of single expression

Opto-Electronics Review ◽

10.2478/s11772-010-0049-0 ◽

2010 ◽

Vol 18 (4) ◽

Cited By ~ 15

Author(s):

H.V. Baghdasaryan ◽

T.M. Knyazyan ◽

T.H. Baghdasaryan ◽

B. Witzigmann ◽

F. Roemer

Keyword(s):

Power Flow ◽

Normal Incidence ◽

Bragg Reflector ◽

Flow Density ◽

Problem Solution ◽

Absorption Loss ◽

Distributed Bragg Reflector ◽

Method Of Single Expression ◽

Quarter Wave ◽

Wavelength Scale

AbstractElectrodynamical model of a classical distributed Bragg reflector (DBR) consisting of alternating quarter-wave layers of high and low permittivity is considered at the plane wave normal incidence. Reflective characteristics of DBR possessing absorption loss in constituting layers are analysed via correct wavelength-scale boundary problem solution by the method of single expression (MSE). Analysis of optical field and power flow density distributions within the lossy DBR structures explained the peculiarities of their reflective characteristics. Optimal configurations of lossless and lossy DBRs are revealed. Specific DBR structures possessing full transparency at definite number of layers are also analysed.

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Simultaneous Monitoring of Wafer- and Environment-States During Molecular Beam Epitaxy

MRS Proceedings ◽

10.1557/proc-441-761 ◽

1996 ◽

Vol 441 ◽

Author(s):

K. J. Knopp ◽

J. R. Ketterl ◽

D. H. Christensen ◽

T. P. Pearsall ◽

J. R. Hill

Keyword(s):

Real Time ◽

Molecular Beam ◽

Incident Angle ◽

Optical Path Length ◽

Bragg Reflector ◽

Length Variation ◽

Distributed Bragg Reflector ◽

The Real ◽

Uv Reflectance ◽

Thickness Variations

AbstractWe report the simultaneous monitoring of the environment-state and wafer-state during epitaxial crystal growth using a single real-time measurement. Atomic absorption spectroscopy (AAS) is used to monitor the incident molecular beam flux while UV reflectance (UVR) at 396 nm with an incident angle of 78° is used to monitor growth on the wafer. We have studied the utility of AAS/UVR monitoring of AlxGa1-xAs deposition: AlAs growing on GaAs, GaAs on AlAs, and superlattice growth. Additionally, optical multichannel spectroscopy (OMS) data were acquired throughout the growth of a distributed Bragg reflector (DBR). The relationship of the structure of the real-time OMS data to absorption, optical path length variation, and differential layer thickness variations is also discussed. Numerical simulations of the real-time wafer-state monitors using pseudodielectric constants, appropriate at a growth temperature of 579 °C, show good agreement with measured spectra.

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