scholarly journals Photoreflectance and Raman Study of Surface Electric States on AlGaAs/GaAs Heterostructures

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Luis Zamora-Peredo ◽  
Leandro García-González ◽  
Julián Hernández-Torres ◽  
Irving E. Cortes-Mestizo ◽  
Víctor H. Méndez-García ◽  
...  
Keyword(s):  
Electric Field ◽  
Penetration Depth ◽  
Layer Thickness ◽  
Surface Passivation ◽  
Electronic States ◽  
Cap Layer ◽  
Raman Study ◽  
Surface Electric Field ◽  
532 Nm ◽  
Good Agreement

Photoreflectance (PR) and Raman are two very useful spectroscopy techniques that usually are used to know the surface electronic states in GaAs-based semiconductor devices. However, although they are exceptional tools there are few reports where both techniques were used in these kinds of devices. In this work, the surface electronic states on AlGaAs/GaAs heterostructures were studied in order to identify the effect of factors like laser penetration depth, cap layer thickness, and surface passivation over PR and Raman spectra. PR measurements were performed alternately with two lasers (532 nm and 375 nm wavelength) as the modulation sources in order to identify internal and surface features. The surface electric field calculated by PR analysis decreased whereas the GaAs cap layer thickness increased, in good agreement with a similar behavior observed in Raman measurements (IL-/ILOratio). When the heterostructures were treated by Si-flux, these techniques showed contrary behaviors. PR analysis revealed a diminution in the surface electric field due to a passivation process whereas theIL-/ILOratio did not present the same behavior because it was dominated by the depletion layers width (cap layer thickness) and the laser penetration depth.

Optical and electrical study of cap layer effect in QHE devices with double-2DEG

2013 ◽  
Vol 1617 ◽  
pp. 31-36 ◽  
Author(s):  
L. Zamora-Peredo ◽  
I. Cortes-Mestizo ◽  
L. García-Gonzáez ◽  
J. Hernández-Torres ◽  
T. Hernandez-Quiroz ◽  
...  
Keyword(s):  
Electric Field ◽  
Room Temperature ◽  
Quantum Hall ◽  
Three Samples ◽  
Cap Layer ◽  
Layer Effect ◽  
Hall Effect Measurements ◽  
Band Profile ◽  
Surface Electric Field ◽  
Dimensional Electron Gas

ABSTRACTIn this work we report on the characteristics of GaAs/AlGaAs heterostructures with a symmetric double two-dimensional electron gas (D-2DEG). Optical characterization was made by room temperature photoreflectance (PR) spectroscopy as well as electrical properties were determinated using the quantum Hall effect measurements at 2K. In order to study the surface effects on the conduction band profile, three samples with different GaAs cap layer thickness (25, 60 and 80 nm) were grown by the molecular beam epitaxy. Photoreflectance spectra at room temperature show the wide-period Franz-Keldysh oscillations between 1.42 and 1.70 eV originated by the surface electric field. The analysis of these oscillations shows that the surface electric field varies from 503 to 120 kV/cm whereas the thickness of the cap layer increases that was produced by the reduction of the depletion zone near the surface. Using QHE measurements we found that electron density increases if the surface electric field decreases.

Strain Effects in InP Dots in between Barriers of GaInP

1995 ◽  
Vol 417 ◽  
Author(s):  
Mats-Erik Pistol ◽  
Srinivasan Anand ◽  
Niclas Carlsson ◽  
Dan Hessman ◽  
Lars Landin ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Strain Tensor ◽  
Blue Shift ◽  
Deformation Potential ◽  
Emission Energy ◽  
Surrounding Matrix ◽  
Cap Layer ◽  
Deformation Potential Theory ◽  
Strong Blue Shift ◽  
Good Agreement

AbstractWe have investigated the photoluminescence emission energy of InP dots as a function of cap layer thickness. We find a strong blue-shift with increasing cap layer thickness. The strain tensor in the dot as well as in the surrounding matrix has been modelled using finite element methods and the band-gap has been calculated using deformation potential theory. We find good agreement between calculation and experiment. For uncapped dots we find that the emission energy is lower than for biaxially strained InP, and is indeed close to unstrained InP.

The Effect of Roughness Features on Mos Surface Electric Field and Fowler-Nordheim Tunneling Behavior

1997 ◽  
Vol 473 ◽  
Author(s):  
Heng-Chih Lin ◽  
Edwin C. Kan ◽  
Toshiaki Yamanaka ◽  
Simon J. Fang ◽  
Kwame N. Eason ◽  
...  
Keyword(s):  
Electric Field ◽  
Three Dimensional ◽  
Tunneling Current ◽  
Gate Oxide ◽  
Oxide Thickness ◽  
Interface Roughness ◽  
Normal Electric Field ◽  
Surface Electric Field ◽  
Tunneling Behavior ◽  
Nordheim Tunneling

ABSTRACTFor future CMOS GSI technology, Si/SiO2 interface micro-roughness becomes a non-negligible problem. Interface roughness causes fluctuations of the surface normal electric field, which, in turn, change the gate oxide Fowler-Nordheim tunneling behavior. In this research, we used a simple two-spheres model and a three-dimensional Laplace solver to simulate the electric field and the tunneling current in the oxide region. Our results show that both quantities are strong functions of roughness spatial wavelength, associated amplitude, and oxide thickness. We found that RMS roughness itself cannot fully characterize surface roughness and that roughness has a larger effect for thicker oxide in terms of surface electric field and tunneling behavior.

scholarly journals Investigations on the Optical Properties of InGaN/GaN Multiple Quantum Wells with Varying GaN Cap Layer Thickness

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Xiaowei Wang ◽  
Feng Liang ◽  
Degang Zhao ◽  
Zongshun Liu ◽  
Jianjun Zhu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Quantum Wells ◽  
Layer Thickness ◽  
Stark Effect ◽  
Chemical Vapor ◽  
Multiple Quantum ◽  
Three Samples ◽  
Measurement Results ◽  
Cap Layer ◽  
The Difference

Abstract Three InGaN/GaN MQWs samples with varying GaN cap layer thickness were grown by metalorganic chemical vapor deposition (MOCVD) to investigate the optical properties. We found that a thicker cap layer is more effective in preventing the evaporation of the In composition in the InGaN quantum well layer. Furthermore, the quantum-confined Stark effect (QCSE) is enhanced with increasing the thickness of GaN cap layer. In addition, compared with the electroluminescence measurement results, we focus on the difference of localization states and defects in three samples induced by various cap thickness to explain the anomalies in room temperature photoluminescence measurements. We found that too thin GaN cap layer will exacerbates the inhomogeneity of localization states in InGaN QW layer, and too thick GaN cap layer will generate more defects in GaN cap layer.

scholarly journals Simulation of Thermal and Electric Field Distribution in Packaged Sausages Heated in a Stationary Versus a Rotating Microwave Oven

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1622
Author(s):  
Wipawee Tepnatim ◽  
Witchuda Daud ◽  
Pitiya Kamonpatana
Keyword(s):  
Temperature Distribution ◽  
Electric Field ◽  
Three Dimensional ◽  
Development Stage ◽  
Microwave Oven ◽  
Computational Time ◽  
Plastic Package ◽  
Heating Uniformity ◽  
The Cost ◽  
Good Agreement

The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision than the stationary model. In addition, the computational time using COMSOL in combination with MATLAB was reduced by 60% compared to COMSOL alone. Consequently, the models could assist food producers and associations in designing packaging materials to prevent leakage of the packaging compound, developing new products and applications to improve product heating uniformity, and reducing the cost and time of the research and development stage.

BICOLOR OPTICAL TREATMENT OF MULTI-LAYERS FILM SAMPLES

2010 ◽  
Vol 24 (08) ◽  
pp. 937-942 ◽  
Author(s):  
K. OZGA ◽  
J. EBOTHÉ ◽  
H. NGUYEN CONG ◽  
D. MARTEL ◽  
W. GRUHN ◽  
...  
Keyword(s):  
Electric Field ◽  
Power Density ◽  
Local Heating ◽  
Independent Measurement ◽  
Yag Lasers ◽  
Optical Susceptibility ◽  
Dc Electric Field ◽  
Optical Treatment ◽  
532 Nm ◽  
Multi Layer Film

In the present paper, we study the influence of simultaneous polarized optical treatment (10 ns Nd: YAG lasers with wavelengths 1064 nm and 532 nm with power density 0.6 GW/cm2) together with electrostatic dc electric field (up to 8 kV/cm) on self-assembled multi-layer film samples. The second-order optical susceptibility (SOS) achieves the maximal values after one minute simultaneous dc electrical-optical treatment. Further treatment will not enhance the values and even leads to the decrease of SOS. The independent measurement of the local temperature shows that local heating does not exceed 10.1 K.

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