Strain relaxation in [001]‐ and [111]‐GaAs/CaF2analyzed by Raman spectroscopy

1995 ◽  
Vol 77 (3) ◽  
pp. 1126-1132 ◽  
Author(s):  
P. Puech ◽  
G. Landa ◽  
R. Carles ◽  
P. S. Pizani ◽  
E. Daran ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Strain Relaxation

Strain relaxation of strained-Si layers on SiGe-on-insulator (SGOI) structures after mesa isolation

2002 ◽  
Vol 738 ◽  
Author(s):  
Koji Usuda ◽  
Tomohisa Mizuno ◽  
Tsutomu Tezuka ◽  
Naoharu Sugiyama ◽  
Yoshihiko Moriyama ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
High Speed ◽  
Strain Relaxation ◽  
Strained Si ◽  
Beam Electron ◽  
Similar Tendency ◽  
Device Structures ◽  
Before And After ◽  
Low Power Cmos ◽  
Si Films

ABSTRACTStrained-Si-On-Insulator (Strained-SOI) MOSFETs are one of the most promising device structures for high speed and/or low power CMOS. In realizing strained-Si MOS LSI, fabrication of strained-Si MOSFETs with small sizes are indispensable and thus, the investigation of the strain relaxation is an important issue. Therefore, the strain relaxation of strained-SOI mesa islands with small active area was investigated in this study. Thin strained-Si films were grown on thin relaxed SiGe-on-insulator (SGOI) structures (x=0.28). The isolation process was carried out by using chemical-dry-etching (CDE) to fabricate samples with small active areas. Using Raman spectroscopy with resolution of > 1 micron meter, strained-Si islands on SGOI substrates with the size of 5 micron meter square were investigated. Rapid-thermal-annealing (RTA) in N2 atmosphere was performed to study the strain relaxation during heating processes. As a result, it was confirmed that the strained-Si layers grown on relaxed SiGe (x=0.28) before and after mesa isolation, down to 5 micron meter in size, had almost no relaxation after the RTA process at 1000°C. Furthermore, it was confirmed that the nano-beam electron diffraction (NBD) measurement showed similar tendency regarding the strain relaxation.

scholarly journals Effect of Strains and V-Shaped Pit Structures on the Performance of GaN-Based Light-Emitting Diodes

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 311 ◽  
Author(s):  
Shuo-Wei Chen ◽  
Chia-Jui Chang ◽  
Tien-Chang Lu
Keyword(s):  
Raman Spectroscopy ◽  
Growth Temperature ◽  
Light Absorption ◽  
Light Emitting Diodes ◽  
Strain Relaxation ◽  
Thick Layer ◽  
Multiple Quantum ◽  
Confocal Raman Spectroscopy ◽  
Light Emitting ◽  
Confocal Raman

Strains and V-shaped pits are essential factors for determining the efficiency of GaN-based light-emitting diodes (LEDs). In this study, we systematically analyzed GaN LED structures on patterned sapphire substrates (PSSs) with two types of growth temperature employed for prestrained layers and three different thickness of n-type GaN layers by using cathodoluminescence (CL), microphotoluminescence (PL), and depth-resolved confocal Raman spectroscopy. The results indicated that V-pits formation situation can be analyzed using CL. From the emission peak intensity ratio of prestrained layers and multiple quantum wells (MQWs) in the CL spectrum, information regarding strain relaxation between prestrained layers and MQWs was determined. Furthermore, micro-PL and depth-resolved confocal Raman spectroscopy were employed to validate the results obtained from CL measurements. The growth conditions of prestrained layers played a dominant role in the determination of LED performance. The benefit of the thick layer of n-GaN was the strain reduction, which was counteracted by an increase in light absorption in thick n-type doped layers. Consequently, the most satisfactory LED performance was observed in a structure with relatively lower growth temperature of prestrained layers that exhibited larger V-pits, leading to higher strain relaxation and thinner n-type GaN layers, which prevent light absorption caused by n-type GaN layers.

Nondestructive Investigation of Heterojunction Interfacial Properties Using Two-Wavelength Raman Spectroscopy on Thin-Film CdS/CdTe Solar Cells

2016 ◽  
Vol 70 (9) ◽  
pp. 1555-1560 ◽  
Author(s):  
Guanggen Zeng ◽  
Paul Harrison ◽  
Ali Kidman ◽  
Alaa Al-mebir ◽  
Lianghuan Feng ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Solar Cells ◽  
Solar Cell ◽  
Strain Relaxation ◽  
Interfacial Properties ◽  
Cell Performance ◽  
Window Layer ◽  
Crystalline Quality ◽  
Misfit Dislocations ◽  
Solar Cell Performance

Raman spectra specific to CdS and CdTe were obtained on the CdS/CdTe heterojunction interface by employing two excitation wavelengths of λ1 = 488 nm and λ2 = 633 nm, respectively, from the glass side of Glass/FTO/CdS/CdTe/HgTe:Cu:graphite/Ag solar cells fabricated using pulsed-laser deposition (PLD). This two-wavelength Raman spectroscopy approach, with one wavelength selected below the absorption edge of the window layer (λ2 in this case), allows nondestructive characterization of the CdS/CdTe heterojunction and therefore correlation of the interfacial properties with the solar cell performance. In this study, the evolution of the interfacial strain relaxation during cell fabrication process was found to be affected not only by the inter-diffusion of S and Te corresponding to the formation of CdS xTe 1–x ternary alloy with a various x from ∼0.01 to ∼0.067, but also by the variation in misfit dislocations (MDs) at CdS/CdTe interface from Raman TO/LO ratio ∼2.85 for as-deposited sample to TO/LO ∼4.44 for the cells post treatment. This is consistent with the change of the Urbach energy from 0.03 eV to 0.09 eV, indicative of the deterioration of crystalline quality of CdTe at interface although improved CdTe crystalline quality was observed away from the interface after the CdCl2 annealing. This difference crucially impacted on the rectification characteristics of the CdS/CdTe heterojunction and therefore the solar cell performance.

Effect of thermal processing on strain relaxation and interdiffusion in Si/SiGe heterostructures studied using Raman spectroscopy

2001 ◽  
Vol 79 (14) ◽  
pp. 2148-2150 ◽  
Author(s):  
S. J. Koester ◽  
K. Rim ◽  
J. O. Chu ◽  
P. M. Mooney ◽  
J. A. Ott ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Thermal Processing ◽  
Strain Relaxation

MonitoringB-site ordering and strain relaxation in NiFe2O4epitaxial films by polarized Raman spectroscopy

2011 ◽  
Vol 83 (1) ◽  
Author(s):  
M. N. Iliev ◽  
D. Mazumdar ◽  
J. X. Ma ◽  
A. Gupta ◽  
F. Rigato ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Strain Relaxation ◽  
Polarized Raman Spectroscopy ◽  
Polarized Raman
Sign in / Sign up

Export Citation Format

Share Document