Home  About us  Contact
 

Single Quantum Wells (single + quantum_well)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

Effect of electric field on the probability of optical transitions in InGaAs/GaAs quantum wells observed by photo- and electroreflectance methods

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2005
A. N. Pikhtin
Abstract The influence of an electric field on the energy spectrum and the probability of optical transitions in InGaAs/GaAs single quantum wells (QWs) of different widths has been investigated with photo- and electroreflectance techniques. The electric field in the area of a QW is varied in a wide range and controlled by well-defined Franz,Keldysh oscillations. A quadratic red shift of electroreflectance features concerned with interband excitonic transitions in QWs is observed. The electric field dependence of the intensity of these features and calculated data for the probability of optical transitions are compared. There are some field values when transitions that are symmetry-forbidden in zero field are much stronger than symmetry-allowed transitions. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Polarization field crossover in semi-polar InGaN/GaN single quantum wells

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2010
H. Shen
Abstract We present an electroreflectance study of the polarization field in semi-polar (10) and (112) oriented InGaN quantum wells (QW). For the () sample, the flat-QW condition (the electric field in the QW is zero) is at a reverse bias voltage. For the (112) sample, the flat-QW condition is at a forward bias voltage larger than the turn on voltage of the diode. However, the flat-barrier condition (the electric field in the barrier region is zero) is at a forward bias voltage less than the turn on voltage of the diode. The flat-QW condition and the flat-barrier condition are determined by examining the zero-crossing and the Franz-Keldysh oscillations in the electroreflectance signal for (10) and (112) InGaN QWs, respectively. From the corresponding bias voltages, we deduce the polarization field in the QWs and conclude that in the semi-polar InGaN/GaN QW there is a crossover angle between the polar and non-polar orientations where the polarization field vanishes. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Time-resolved photoluminescence and steady-state optical studies of GaInNAs and GaInAs single quantum wells

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2007
Y. Sun
Abstract Time-resolved photoluminescence spectroscopy is used to investigate carrier dynamics of Ga1,xInxNyAs1,y (x , 0.33, y , 0.01) single quantum well (QW) structures. PL spectra measured as a function of temperature together with the PL decay times at wavelengths around and below the PL peak energy are used to determine de-trapping activation energies and time constants. The results are interpreted in terms of simultaneous thermal excitation of deep localized excitons to shallow localized states. According to the model, with increasing temperatures, localized excitons gain enough thermal energy to populate the free exciton states in quantum well with shorter lifetimes due to coherent nature of free excitons. In addition, at temperatures around and above 80 K, more non-radiative channels become available to compete with the radiative processes leading to shorter time constants. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

The growth of In-rich InGaN/GaN single quantum wells by metalorganic chemical vapor deposition

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2003
Hyun Jin Kim
Abstract In-rich InGaN/GaN single quantum wells were grown by metalorganic chemical vapor deposition for the first time to the best of our knowledge. The structures consist of a 2-,m thick GaN buffer layer, a 2-nm thick In-rich InGaN single quantum well, and a 20 nm thick GaN capping layer. Single quantum well structures were examined by transmission electron microscopy. Photoluminescence emissions from the single quantum well samples were observed at wavelengths ranged from 400 nm to 500 nm depending upon the growth conditions of the InN layer. From a simple energy level calculation, we found the possibility of extremely large emission peak shift with well thickness. [source]