A detailed analysis of the energy levels configuration existing in the band gap of supersaturated silicon with titanium for photovoltaic applications

Pérez, E. and Dueñas, S. and Castán Lanaspa, Helena and Bailón Vega, Luis Alberto and Montero, D. and García Hernánsanz, Ramiro and García Hemme, Eric and Olea, J. and González Díaz, Germán (2015). A detailed analysis of the energy levels configuration existing in the band gap of supersaturated silicon with titanium for photovoltaic applications. "Journal of Applied Physics", v. 18 (n. 24); pp.. ISSN 0021-8979. https://doi.org/10.1063/1.4939198.

Description

Title: A detailed analysis of the energy levels configuration existing in the band gap of supersaturated silicon with titanium for photovoltaic applications
Author/s:
  • Pérez, E.
  • Dueñas, S.
  • Castán Lanaspa, Helena
  • Bailón Vega, Luis Alberto
  • Montero, D.
  • García Hernánsanz, Ramiro
  • García Hemme, Eric
  • Olea, J.
  • González Díaz, Germán
Item Type: Article
Título de Revista/Publicación: Journal of Applied Physics
Date: 2015
ISSN: 0021-8979
Volume: 18
Subjects:
Faculty: Instituto de Energía Solar (IES) (UPM)
Department: Electrónica Física
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

The energy levels created in supersaturated n-type silicon substrates with titanium implantation in the attempt to create an intermediate band in their band-gap are studied in detail. Two titanium ion implantation doses (1013cm-2 and 1014cm-2) are studied in this work by conductance transient technique and admittance spectroscopy. Conductance transients have been measured at temperatures of around 100 K. The particular shape of these transients is due to the formation of energy barriers in the conduction band, as a consequence of the band-gap narrowing induced by the high titanium concentration. Moreover, stationary admittance spectroscopy results suggest the existence of different energy level configuration, depending on the local titanium concentration. A continuum energy level band is formed when titanium concentration is over the Mott limit. On the other hand, when titanium concentration is lower than the Mott limit, but much higher than the donor impurity density, a quasi-continuum energy level distribution appears. Finally, a single deep center appears for low titanium concentration. At the n-type substrate, the experimental results obtained by means of thermal admittance spectroscopy at high reverse bias reveal the presence of single levels located at around Ec-425 and Ec-275 meV for implantation doses of 1013cm-2 and 1014cm-2, respectively. At low reverse bias voltage, quasi-continuously distributed energy levels between the minimum of the conduction bands, Ec and Ec-450 meV, are obtained for both doses. Conductance transients detected at low temperatures reveal that the high impurity concentration induces a band gap narrowing which leads to the formation of a barrier in the conduction band. Besides, the relationship between the activation energy and the capture cross section values of all the energy levels fits very well to the Meyer-Neldel rule. As it is known, the Meyer-Neldel rule typically appears in processes involving multiple excitations, like carrier capture and emission in deep levels, and it is generally observed in disordered systems. The obtained Meyer-Neldel energy value, 15.19 meV, is very close to the value obtained in multicrystalline silicon samples contaminated with iron (13.65 meV), meaning that this energy value could be associated to the phonons energy in this kind of substrates. © 2015 AIP Publishing LLC.

Funding Projects

TypeCodeAcronymLeaderTitle
Madrid Regional GovernmentP2013/MAE-2780UnspecifiedUnspecifiedUnspecified
Government of SpainTEC2013-41730-RUnspecifiedUnspecifiedFabricación de dispositivos detectores de infrarrojo próximo mediante si supersaturado con metales de transición
Government of SpainJCI-2011-10402UnspecifiedUnspecifiedUnspecified
Government of SpainTEC2014-52152-C3-3-RUnspecifiedUnspecifiedCaracterización eléctrica de estructuras MIS y MIM con dieléctricos de alta permitividad para su aplicación en RRAMS y MEMRISTORES

More information

Item ID: 43612
DC Identifier: http://oa.upm.es/43612/
OAI Identifier: oai:oa.upm.es:43612
DOI: 10.1063/1.4939198
Official URL: http://scitation.aip.org/content/aip/journal/jap/118/24/10.1063/1.4939198
Deposited by: Memoria Investigacion
Deposited on: 26 Oct 2016 16:08
Last Modified: 07 Jun 2019 18:26
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