Fractal quantum well heterostructures for broadband light emitters
We examine carrier relaxation and radiative recombination in AlGaAs based near IR and AlGaInP based visible fractal quantum well heterostructures. Through temperature dependent photoluminescence, we demonstrate that enhanced population of higher lying energy levels can be achieved by varying the thickness of the layers in the fractal heterostructurd. This distribution of carriers results in room temperature emission over a relatively broad range of wavelengths: approximately 700--855 nm for AlGaAs structures and 575--650 nm for AlGaInP structures. Spectra are compared to theoretical calculations to evaluate the non-equilibrium nature of the carrier distributions. Time resolved photoluminescence measurements demonstrate an approximately linear relationship between the radiative decay time and the layer thickness of the structure. Correspondingly, integrated luminescence measurements at room temperature reveal a factor of four increase in the light output efficiency of the structure as the fractal layer thickness is increased from 50 {angstrom} to 400 {angstrom}. The applicability of these heterostructures to broadband LEDs is discussed.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 37988
- Report Number(s):
- SAND-94-2169C; CONF-950226-31; ON: DE95009579
- Resource Relation:
- Conference: SPIE `95: SPIE conference on optics, electro-optics, and laser application in science, engineering and medicine, San Jose, CA (United States), 5-14 Feb 1995; Other Information: PBD: [1994]
- Country of Publication:
- United States
- Language:
- English
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