2014 Les durées de vie mesurées à partir des photoréponses de conductivité (sous courant ou tension constants de polarisation), de courant de diffusion et de tension de circuit ouvert, créées par excitation transitoire de porteurs, sont considérées. Partant des expressions analytiques, la discussion porte sur les expressions clef, les conditions de validité et les applications de chacune des méthodes discutées, en supposant une excitation uniforme de porteurs dans un échantillon unidimensionnel et homogène; la discussion tient compte des caractéristiques de l'échantillon (épaisseur W, durée de vie volumique 03C4v, vitesses de recombinaison aux surfaces s1,2, coefficient de diffusion D des porteurs minoritaires et densité d'équilibre en porteurs majoritaires p0), de la densité de porteurs en excès 0394p, de la durée T de l'impulsion lumineuse et des temps t auxquels la réponse est considérée. L'étude expérimentale porte surtout sur des échantillons de silicium d'épaisseur jusqu'à 1 mm, éclairés par des impulsions laser de durée T = 2 à 30 ns. Les réponses à une lumière pénétrante (03BB = 1,06 03BCm, 03B1 = 40 cm-1 dans le silicium usuel; 0394p = 10-4 à 102 p0) et à une lumière fortement absorbée (03BB = 0,69 ou 0,53 03BCm, 03B1 = 2 x 103 et 104 cm-1 ; intensité du faisceau E0 = 10-4 à 103 mJ/cm2) sont utilisées pour montrer sous quelles conditions les photoréponses observées conduisent aux mêmes valeurs mesurées de la durée de vie des porteurs, et donnent une mesure de leur durée de vie volumique.Abstract. 2014 Carrier lifetime measurements from photoconductivity (with constant current and constant voltage polarizations of the sample), diffusion photocurrent and open circuit photovoltage responses to transient carrier excitation are compared. Using analytical expressions, the key expressions, conditions of validity and applications of each method are discussed, assuming uniform carrier injection in an unidimensional sample of homogeneous material; the discussion is done taking into account the sample characteristics (width W, bulk lifetime 03C4v, surface recombination velocities s1,2, minority carrier diffusion coefficient D, equilibrium majority carrier density p0), excess carrier density 0394p, light pulse duration T and times t of the response considered. The experimental study especially deals with silicon samples up to W = 1 mm thick, illuminated by T = 2 ns to 30 ns laser beams.The responses to penetrating light (03BB = 1.06 03BCm, 03B1 = 40 cm-1 in ordinary silicon, 0394p = 10-4 to 102 p0) and strongly absorbed light (03BB = 0.69 or 0.53 03BCm, 03B1 = 2 x 103 and 104 cm-1, beam intensity E0 = 10-4 to 103 mJ/cm2) are used to show the conditions under which the photoresponses observed lead to the same measured values of carrier lifetime and give bulk lifetime measurement.

High injection changes in carrier lifetime, mobility and density of a semiconductor material are analyzed using the changes in carrier recombination or diffusion processes and in equilibrium of the donor-acceptor centers (including defect centers). The analysis especially involves the variations with carrier injection Δ of state charge q0 and energy level E occupancy state nE(pE) of the material recombination or donor (acceptor) centers, taking into account the Δ, band-gap energy level E, material Fermi-level EF and center capture cross section σ cn,p values. The above variations and high injection changes are then discussed in terms of their effects on the magnitude, rise and decay of the material transient photoresponses of conductivity Δ V(t) and minority carrier diffusion current iD(t). High injection effects on the conditions under which these photoresponses are observed are also pointed out in this paper. With the view of illustrating the above analysis, experimental results are shown which deal with ~ 1 and 10 Ω.cm P-type silicon samples, submitted to Δ ~ 10-3 to 103 × p0 carrier injection by neodymium laser pulses of 55 ns duration. Low dose irradiation by 14 MeV neutrons (9.6 x 1011 n.cm-2) is used to demonstrate the role of material defects in high injection phenomena. Using the comparison between the photoconductivity and minority carrier diffusion current measured responses, the results especially show that acceptor centers are created by the irradiation (E A = Ev + 0.09 eV, σcp = 10-17 cm-2) whose effect is to lower the effects due to the previously existing donor centers (ED ∼ Ec - 0.08 eV, σcn ~ 1.5 × 10-18, in the un-irradiated samples)