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We report time-resolved photoluminescence measurements on a set of long-wave infrared InAs/GaSb type II superlattice absorber samples with various widths as a function of temperature and excitation density. Careful analysis of the photoluminescence data determines the minority carrier lifetime and background carrier density as a function of temperature, and provides information on the acceptor energy and density in each sample. Results indicate that carrier lifetime is dominated by Shockley-Read-Hall recombination with a lifetime of ~30 ns at 77 K for all samples. Below 40 K, background carriers are observed to freeze-out in conjunction with increased contributions from radiative recombination. An acceptor energy level of ~20 meV above the valance band is also determined for all samples. Variations of carrier lifetime between each sample do not strongly correlate with absorber width, indicating that barrier recombination is not the dominant factor limiting the carrier lifetime in our samples.

GaInSb and AlGaInSb compositionally graded buffer layers grown on GaSb by MBE were used to develop unrelaxed InAs_1-xSb_x epitaxial alloys with strain-free native lattice constants up to 2.1% larger than that of GaSb. The in-plane lattice constant of the strained top buffer layer was grown to be equal to the native, unstrained lattice constant of InAs_1-xSb_x with given x. The InAs_0.56Sb_0.44 layers demonstrated a photoluminescence (PL) peak at 9.4 μm at T = 150 K. The minority carrier lifetime measured at 77 K for InAs_0.8Sb_0.2 was 250 ns.

We have grown orthorhombic barium disilicide (${\mathrm{\text{BaSi}}}_2$) thin-films on modified silicon (Si) substrates by a thermal evaporation method. The surface modification of Si substrate was performed by a metal-assisted chemical etching method. The effects of etching time $t_e$ on crystalline quality as well as optical and electrical properties of the ${\mathrm{\text{BaSi}}}_2$ films were investigated. The obtained results showed that substrate modification can enhance the crystalline quality and electrical properties; reduce the light reflection; and increase the absorption of the ${\mathrm{\text{BaSi}}}_2$ thin-films. The $t_e$ of 8 s was chosen as the optimized condition for surface modification of Si substrate. The achieved inferred short-circuit current density, Hall mobility, and minority carrier lifetime of the ${\mathrm{\text{BaSi}}}_2$ film at $t_e$ of 8 s were $38{\mathrm{\text{mA/cm}}}^2$, $273{\mathrm{\text{cm}}}^2/\mathrm{\text{Vs}}$, and $2.3\mu$s, respectively. These results confirm that the ${\mathrm{\text{BaSi}}}_2$ thin-film evaporated on the modified Si substrate is a promising absorber for thin-film solar cell applications.

The aim of this paper is to study the effect of erbium oxide (Er₂O₃) on porous silicon (PS) wafers used for photovoltaic application. An immersion of PS wafers in Er₂O₃ solution can be used to enhance light trapping and form an efficient surface by passivation process. PS was prepared by the stain-etching method and doped by Er species. In fact, the topography was investigated by the scanning electron microscope (SEM). In addition, the spectral behaviors of the reflectivity and the photoluminescence were discussed. The dependence of minority carrier lifetime was evaluated by means of the Quasi-Steady-State Photoconductance technique (QSSPC). Besides, an enhancement in lifetime was observed. A framework is provided for estimating an efficiency improvement in studied films which will help to guide the development of improved energy-efficient.

The chemical etching of the surface of silicon wafers is a critical step in the manufacturing process of all semiconductor devices. In this contribution, we investigate the effect of alkaline etching on minority carrier lifetime and interface-states density ($D_{\mathrm{\text{it}}})$ of silicon wafers intended to be used as solar cell substrates. After alkali treatment, the surface morphology was analyzed using scanning electron microscopy (SEM) and UV-visible-NIR optical spectroscopy. Besides and as electrical characterizations, the minority charge carrier lifetime (${\tau }_{\mathrm{\text{n}}})$ was measured by the Quasi-Steady State Photoconductance technique (QSSPC), and the Electrochemical Impedance Spectroscopy was used to evaluate $D_{\mathrm{\text{it}}}$. These results were correlated with the surface recombination velocity (SRV) calculated by fitting the experimental data to the theory. The results of characterization showed a lower SRV and a higher apparent lifetime (${\tau }_{\mathrm{\text{app}}})$ obtained with 23wt.% KOH etching as compared to those obtained with 30wt.% NaOH; viz. 825cm$\cdot {\mathrm{\text{s}}}^{-1}$ against 1500cm.s${}^{-1}$ and 32$\mu$s against 23$\mu$s, respectively. These findings were corroborated by $D_{\mathrm{\text{it}}}$ measurements which gave $1.55\times 10^{11}$ev${}^{-1}$cm${}^{-2}$ for KOH treatment and $5.67\times 10^{12}$ev${}^{-1}$cm${}^{-2}$ for NaOH treatment.