Université de Neuchâtel

Wafer sawing processes : from microscopic phenomena to macroscopic properties

Bidiville, Adrien ; Ballif, Christophe (Dir.) ; Rooij, Nico de (Codir.)

Thèse de doctorat : Université de Neuchâtel, 2010.

The majority of the solar modules are based on crystalline silicon (c-Si) wafers. Whereas the c-Si technology can offer a high efficiency, its main drawback (compared to traditional means to produce electricity) is the cost. The wafers account for one third of the total module cost, as high purity (thus expensive) silicon is required. One way to decrease the solar electricity cost is to decrease...

Université de Neuchâtel

Characterizazion of time resolved photodetector systems for Positron Emission Tomography

Powolny, François ; Ballif, Christophe (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2009 ; Th. 2107.

The main topic of this work is the study of detector systems composed of a scintillator, a photodetector and readout electronics, for Positron Emission Tomography (PET). In particular, the timing properties of such detector systems are studied. The first idea is to take advantage of the good timing properties of the NINO chip, which is a fast preamplifier-discriminator developed for the ALICE...

Université de Neuchâtel

Low pressure chemical vapor deposited Zinc Oxide for thin film silicon solar cells : optical and electrical properties

Steinhauser, Jérôme ; Ballif, Christophe (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2008 ; Th. 2099.

Transparent conductive oxides (TCO), such as LPCVD ZnO:B (low pressure chemical vapor deposited zinc oxide doped with boron), play a major role as contacts in thin film silicon photovoltaic solar cells. This document study the "LPCVD ZnO:B layers, from the deposition process to the final application" and focus especially on their electrical and optical properties. This work intended on...

Université de Neuchâtel

Single and multi-junction thin film silicon solar cells for flexible photovoltaics

Söderström, Thomas ; Ballif, Christophe (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2009 ; Th. 2082.

This thesis investigates amorphous (a-Si:H) and microcrystalline (µc-Si:H) solar cells deposited by very high frequency plasma enhanced chemical vapor deposition (VHFPECVD) in the substrate (n-i-p) configuration. It focuses on processes that allow the use of non transparent and flexible substrates such as plastic foil with Tg < 180°C like polyethylene-naphtalate (PEN). In the first...

Université de Neuchâtel

Properties of interfaces in amorphous / crystalline silicon heterojunctions

Olibet, Sara ; Ballif, Christophe (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2008 ; Th. 2066.

The main focus of this work is the study of interfaces in amorphous/crystalline silicon (a-Si:H/c-Si) heterostructures, especially the investigation of the a-Si:H/c-Si heterointerface's electronic quality and its effect on the consecutive a-Si:H/c-Si heterojunction (HJ) solar cell fabrication. c-Si based solar cells have the potential for achieving high conversion efficiencies, but the standard...

Université de Neuchâtel

Electrical and mechanical charaterization of silicon and zinc oxide nanowires

Hoffmann, Samuel ; Ballif, Christophe (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2008 ; Th. 2067.

Semiconducting nanowires can be grown epitaxially on crystalline substrates in predefined directions. This bottom up approach stands in contrast to the common top down technology in semiconductor industry. With diameters down to a few nanometers, the nanowires’ small dimensions open up new possibilities for sensors and electronic devices. This thesis deals with the electrical,...