THERMAL WAVE PROBING OF THE OPTICAL ELECTRONIC AND THERMAL-PROPERTIES OF SEMICONDUCTORS

Over the past 10 years, the field of photothermal wave inspection of semiconductors has undergone much development in many directions such as spectroscopy, thermal characterization and determination of transport properties. The aim of this paper is to introduce understanding and awareness of thermal wave techniques and their potential to the community of semiconductor scientists. Our paper will be organized as follows. Firstly we shall present a detailed review of thermal wave physics and detection techniques. A set-up based on "mirage" detection will be described in detail. Next we shall explore the spectroscopic capabilities of a photothermal experiment in the case of both bulk and layered compounds. The emphasis will be placed on amorphous silicon thin film characterization and on the unique capability of this method to discriminate between the spatial distributions of absorbing centres. Through this kind of experiment, thermal parameters such as diffusivity and effusivity can be obtained. Then we shall discuss the ability of photothermal techniques to monitor semiconductor phenomena at the electronic level. We shall show that electronic transport processes and non-radiative relaxation mechanisms can be successfully probed in situ in photo-excited bulk materials. Finally we shall consider the imaging capabilities of thermal wave techniques with focus on the measurement of semiconductor parameters such as ion implant profiles, electronic surface states and thermal diffusivities at the wafer or processed device level. © 1990.