On the surface characterization in semiconductor structures using the photoacoustic technique

Surface passivation is an extremely important step for high-performance sem iconductor electronic devices, well characterized by the surface recombinat ion velocity, S. In the last years great attention is devoted to the develo pment of methods to reduce the value of this magnitude. In evaluating the a dvantages or drawbacks of a method with respect to another to improve the s urface, it arises the problem of the estimation of S. In this work ne repor t about the application of the photoacoustic (PA) technique to the measurem ent of S at the interface between semiconductor substrates and epitaxial la yers grown on their surfaces. We present theoretical models to the calculat ion of the PA signal for various cases of technological interest as well as experimental results obtained in the material systems SiN(H)/Si, AlGaAs/Ga As and GaInAsSb/GaSb. The obtained values for S were correlated with measur ements performed by conventional methods such as PL and C-V. This work is a new step towards the better understanding of the generation of the PA sign al in semiconductors and in demonstrating the possibilities of the PA techn ique to perform the characterization of semiconductor materials.