Bound-exciton recombination in MgxZn1-xO thin films

2009 ◽  
Vol 1201 ◽  
Author(s):  
Christof Peter Dietrich ◽  
Alexander Müller ◽  
Marko Stölzel ◽  
Martin Lange ◽  
Gabriele Benndorf ◽  
...  
Keyword(s):  
Line Broadening ◽  
Time Resolved ◽  
Type Composition ◽  
Recombination Processes ◽  
Disorder Potential ◽  
Random Disorder ◽  
Spectrally Resolved ◽  
Inhomogeneous Line Broadening ◽  
Time Resolved Photoluminescence ◽  
Inhomogeneous Line

AbstractExcitons in semiconductor alloys feel a random disorder potential leading to inhomogeneous line broadening and a lack of knowledge about the dominating recombination processes. Nevertheless, we demonstrate competing localization effects due to disorder (random potential fluctuations) and shallow point defects. We were able to spectrally separate donor-bound and quasi-free excitons within the whole wurtzite-type composition range of MgxZn1-xO (0 ≤ x ≤ 0.33) using spectrally resolved (x ≤ 0.06) and time-resolved photoluminescence (x ≥ 0.08). We found out that donor-bound excitons dominate photoluminescence spectra even for Mg-contents up to x = 0.18 and still appear for x = 0.33.

Excitation of transitions between atomic or molecular energy levels by monochromatic laser radiation - II. Excitation under conditions of strictly inhomogeneous line broadening and mixed homogeneous and inhomogeneous broadening

1978 ◽  
Vol 362 (1708) ◽  
pp. 13-25 ◽  
Keyword(s):  
Laser Radiation ◽  
Line Width ◽  
Energy Levels ◽  
Incident Radiation ◽  
Exciting Radiation ◽  
Half Line ◽  
Line Broadening ◽  
Moment Matrix ◽  
Inhomogeneous Line Broadening ◽  
Inhomogeneous Line

The development with time of the excitation of a transition between two atomic or molecular energy levels under the influence of monochromatic laser radiation is examined under conditions of strictly inhomogeneous line broadening due to such causes as doppler shift arising from translational velocity. The ratio of the number of molecules, N 2 , in an excited state to the total number, N , is calculated for various ratios of the intensity parameter β ═ E 0 μ / ħ to the half line-width ∆ , where E 0 is the amplitude of the electric field in the incident radiation and is the dipole moment matrix element for the transition. Excitation functions obtained in a previous paper (I) for various values of the ratio γ/β , where γ is the half line-width in the absence of inhomo­geneous broadening, are used to obtain the variation of N 2 / N with time under conditions of mixed broadening for various values of the ratio γ/∆ and γ/β , when the exciting radiation is in exact resonance with the central frequency of the transition.

Delay-Time Statistics and Inhomogeneous Line Broadening in Superfluorescence

1980 ◽  
Vol 45 (7) ◽  
pp. 558-561 ◽  
Author(s):  
Fritz Haake ◽  
Joseph Haus ◽  
Harald King ◽  
Guntram Schröder ◽  
Roy Glauber
Keyword(s):  
Delay Time ◽  
Line Broadening ◽  
Inhomogeneous Line Broadening ◽  
Inhomogeneous Line

scholarly journals Time Resolved Optical Studies of InGaN Layers Grown on LGO

2002 ◽  
Vol 743 ◽  
Author(s):  
Maurice Cheung ◽  
Gon Namkoong ◽  
Madalina Furis ◽  
Fei Chen ◽  
Alexander. N. Cartwright ◽  
...  
Keyword(s):  
Structural Quality ◽  
Photoluminescence Intensity ◽  
X Ray Diffraction ◽  
Optical Studies ◽  
Time Resolved ◽  
Lattice Match ◽  
Spatially Resolved ◽  
Recombination Processes ◽  
Time Resolved Photoluminescence ◽  
Intensity Decay

ABSTRACTRadiative recombination processes in bulk InGaN grown by molecular beam epitaxy (MBE) on lithium gallate (LGO or LiGaO2) substrates were investigated using microscopic PL and time-resolved photoluminescence (TRPL). The improved structural quality resulting from a better lattice match of the LGO substrate to III-V nitride materials simplifies these investigations because well-defined composition phases can be analyzed for both homogeneous and phased separated InGaN samples. Epilayers of InGaN intentionally grown with and without indium segregation were studied. X-ray diffraction measurements showed that the homogeneous epilayer was high quality In0.208Ga0.702N and the segregated epilayer exhibited peaks corresponding to both In0.289Ga0.711N and In0.443Ga0.557N indicating the presence of higher In concentration regions in this sample. Spatially resolved photoluminescence spectra confirm the existence of these regions. The photoluminescence intensity decay is non-exponential for both samples and a stretched exponential fit to the decay data confirms the existence of local potential fluctuations in which carriers are localized before recombination.

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