Films minces à base de Si nanostructuré pour des cellules ...

Chapter 5
Photoluminescence emission modeling in Si-based
thin lms
tel-00916300, version 1 - 10 Dec 2013
5.1 Introduction
The emission properties of Si-based thin lms can be tuned by playing with various
factors such as refractive index, total thickness, sublayer thickness, type of emitters,
concentration of emitters etc., as demonstrated in chapters 3 and 4. The results
of the previous chapters suggested that there might be several kinds of emitters
in the thin lm that contribute to the position, intensity and shape of emission
peaks. A thin lm is assumed to be a multi-wave interferometer such as the plane
parallel plate, of thickness d and a refractive index ñ. Therefore, the reection
and transmission coecients at the air-lm and lm-subtrate interfaces, and the
phaseshift due to the optical path within the thin lm may lead to the interference
eects in PL. Such eects were observed in cathodoluminescence studies of SiO 2
thin lm on Si substrate and investigated as early as 1970s and 1980s [Mitchell 73,
Holm 82]. It has been pointed out that oxide lms thicker than 200 nm exhibit
interference eects [Nesheva 02]. Besides, it has also been reported in SRSO lms
that thickness, refractive index, interface states, along with other experimental setup
parameters such as angle of the incident pump, its power density etc., also play
a role in the photoluminescence spectra [Ternon 04b, Ferre 05]. Therefore, in this
chapter emission modeling will be performed accounting for the following parameters
that are broadly classied into two parts:
1. Incident pump: wavelength, amplitude, angle of incidence.
2. Emission: thin lm thickness, refractive index, population prole of emitters
in the ground and excited states, distribution of emitters in single layers and
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