Comparison between transient and frequency modulated excitation: Application to silicon nitride and aluminum oxide coatings of silicon

Abstract

Contactless measurements of the lifetime of charge carriers are presented with varying ways of photo excitation: with and without bias light and pulsed and frequency modulated. These methods are applied to the study of the surface passivation of single crystalline silicon by a-SiN(x):H and Al2O3 coatings. The properties of these coatings are investigated under consideration of the merits of the different methods.

Analysis of the Surface Passivation Mechanisms of p-Doped Crystalline Silicon by Two Different Al<sub>2</sub>O<sub>3</sub> Coatings via Transient Photo-Conductance Measurements

“…• This works point out that the density of states at the ILGAR-Al 2 O 3 interface has a strong influence on charge carrier kinetics and may hinder its application. A strong influence of the substrate pretreatment cannot be excluded [18]. • The decrease of the degree of passivation by annealing at 425˚C indicates that the temperature stability of the SC-Al 2 O 3 is unsatisfactory.…”

“…However, this depends on the evolution of these processes under stationary illumination. Preliminary results suggest a stationary state which is characterized by a relatively low surface recombination rate [18] and so this interface offers a useful passivation of the p-Si surface.…”

Development of a microwave photoconductance measurement technique for the study of carrier dynamics in highly-excited 4H-SiC

“…The method allows the direct determination of the excess carrier lifetime using a pulsed-laser optical excitation scheme in conjunction with the rectangular waveguide microwave reflectance measurement technique operating at a small acsignal (nearly linear response) and low-injection conditions (i.e. at small perturbations of sample conductivity) [1,4,5]. As the microwave absorption is dependent on the sample conductance and the squared microwave electric field strength E ac in the illuminated area, the E ac amplitude may change under high excitation conditions either due to the skin effect or the external field screening due to the depolarization effect.…”