Excited state carrier dynamics in CdSxSe1-x semisconductor alloys as studied by ultrafast fluorescence spectroscopy
- Univ. of California, Berkeley, CA (United States)
This dissertation discusses studies of the electron-hole pair dynamics of CdSxSe1-x semiconductor alloys for the entire compositional range from x = 1 to x = 0 as examined by the ultrafast fluorescence techniques of time correlated single photon counting and fluorescence upconversion. Specifically, samples with x = 1, .75, .5, .25, and 0 were studied each at a spread of wavelengths about its respective emission maximum which varies according to λ = 718nm - 210x nm. The decays of these samples were found to obey a Kohlrausch distribution, exp [(t/τ)β], with the exponent 3 in the range .5-.7 for the alloys. These results are in agreement with those expected for localization due to local potential variations resulting from the random distribution of sulfur and selenium atoms on the element VI A sub-lattice. This localization can be understood in terms of Anderson localization of the holes in states whose energy distribution tails into the forbidden energy band-gap. Because these states have energy dependent lifetimes, the carriers can decay via many parallel channels. This distribution of channels is the ultimate source of the Kohlrausch form of the fluorescence decays.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE; National Science Foundation (NSF); Department of Defense (DOD)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 108150
- Report Number(s):
- LBL-37588; ON: DE96000115; TRN: 95:007069
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); PBD: Aug 1995
- Country of Publication:
- United States
- Language:
- English
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