Lon-irradiated In0.53Ga0.47As based photoconductive antennas excited at 1.55 mu m for time domain terahertz spectroscopy

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Terahertz radiation from heavy-ion-irradiated In0.53Ga0.47_{0.53}Ga_{0.47}As photoconductive antenna excited at 1.55 μ\mum

We investigate terahertz (THz) emission from heavy-ion-irradiated In0.53Ga0.47As photoconductive antennas excited at 1550 nm. The carrier lifetime in the highly irradiated In0.53Ga0.47As layer is less than 200 fs, the steady-state mobility is 490 cm2 V–1 s–1, and the dark resistivity is 3 Omega cm. The spectrum of the electric field radiating from the Br+-irradiated In0.53Ga0.47As antenna extends beyond 2 THz. The THz electric field magnitude is shown to saturate at high optical pump fluence, and the saturation fluence level increases with the irradiation dose, indicating that defect center scattering has a significant contribution to the transient mobility

1/f noise as function of thickness in Al-doped ZnO thin films

\u3cp\u3eAZO thin films were prepared on glass substrate by RF sputtering at room temperature. The sheet resistance, R\u3csub\u3esh\u3c/sub\u3e [Ω] the resistivity, ρ[Ω.cm] and the 1/f noise were studied as a function of thickness, t from 50 nm to 450 nm. The 1/f noise normalized for bias, frequency and unit area, C\u3csub\u3eus\u3c/sub\u3e is proportional with the sheet resistance R\u3csub\u3esh\u3c/sub\u3e. Our results show that the resistivity decreases with thickness. The ratio K = C\u3csub\u3eus\u3c/sub\u3e/R\u3csub\u3esh\u3c/sub\u3e is proportional to t\u3csup\u3e2\u3c/sup\u3e, which indicates that mobility and the noise parameter α\u3csub\u3eH\u3c/sub\u3e shrink with a shrinking thickness.\u3c/p\u3

Unleashing meiotic crossovers in crops

Improved plant varieties are important in our attempts to face the challenges of a growing human population and limited planet resources. Plant breeding relies on meiotic crossovers to combine favourable alleles into elite varieties1. However, meiotic crossovers are relatively rare, typically one to three per chromosome2, limiting the efficiency of the breeding process and related activities such as genetic mapping. Several genes that limit meiotic recombination were identified in the model species Arabidopsis thaliana2. Mutation of these genes in Arabidopsis induces a large increase in crossover frequency. However, it remained to be demonstrated whether crossovers could also be increased in crop species hybrids. We explored the effects of mutating the orthologues of FANCM3, RECQ44 or FIGL15 on recombination in three distant crop species, rice (Oryza sativa), pea (Pisum sativum) and tomato (Solanum lycopersicum). We found that the single recq4 mutation increases crossovers about three-fold in these crops, suggesting that manipulating RECQ4 may be a universal tool for increasing recombination in plants. Enhanced recombination could be used with other state-of-the-art technologies such as genomic selection, genome editing or speed breeding6 to enhance the pace and efficiency of plant improvement.Université Fédérale de Toulous