Extraction of the defect density of states in microcrystalline silicon from experimental results and simulation studies
| Autor: | T. Tibermacine, M. Ledra, Amar Merazga, N. Ouhabab |
|---|---|
| Rok vydání: | 2015 |
| Předmět: |
Photocurrent
Valence (chemistry) Materials science Analytical chemistry Chemical vapor deposition Condensed Matter Physics Molecular physics Electronic Optical and Magnetic Materials Microcrystalline silicon Attenuation coefficient Materials Chemistry Transient photocurrent Density of states Electrical and Electronic Engineering Spectroscopy |
| Zdroj: | Journal of Semiconductors. 36:093001 |
| ISSN: | 1674-4926 |
| DOI: | 10.1088/1674-4926/36/9/093001 |
| Popis: | The constant photocurrent method in the ac-mode (ac-CPM) is used to determine the defect density of states (DOS) in hydrogenated microcrystalline silicon (μc-Si:H) prepared by very high frequency plasma-enhanced chemical vapor deposition (VHF-PECVD). The absorption coefficient spectrum (ac-α (hν)), is measured under ac-CPM conditions at 60 Hz. The measured ac-α (hν) is converted by the CPM spectroscopy into a DOS distribution covering a portion in the lower energy range of occupied states. We have found that the density of valence band-tail states falls exponentially towards the gap with a typical band-tail width of 63 meV. Independently, computer simulations of the ac-CPM are developed using a DOS model that is consistent with the measured ac-α (hν) in the present work and a previously measured transient photocurrent (TPC) for the same material. The DOS distribution model suggested by the measurements in the lower and in the upper part of the energy-gap, as well as by the numerical modelling in the middle part of the energy-gap, coincide reasonably well with the real DOS distribution in hydrogenated microcrystalline silicon because the computed ac-α (hν) is found to agree satisfactorily with the measured ac-α (hν). |
| Databáze: | OpenAIRE |
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