Voltage controlled terahertz transmission through GaN quantum wells

We report measurements of radiation transmission in the 0.220--0.325 THz frequency domain through GaN quantum wells grown on sapphire substrates at room and low temperatures. A significant enhancement of the transmitted beam intensity with the applied voltage on the devices under test is found. For a deeper understanding of the physical phenomena involved, these results are compared with a phenomenological theory of light transmission under electric bias relating the transmission enhancement to changes in the differential mobility of the two-dimensional electron gas

Variation in Women’s Mate Preferences Over the Development of a Monogamous Relationship Corresponds with Changes in Men’s Life History Strategy

Much research has examined how men’s mating strategies change over the development of a relationship consistent with predictions from Life History Theory. Specifically, research shows both physiological and behavioural indicators of mating effort decrease once men are mated, and further once they become fathers, unless they remain engaged in mating effort. This switch from mating to parenting effort is sexually selected, and therefore the corresponding shifts in women should be examined, though to date, women’s short- or long-term mate preferences have been studied as separate entities rather than as a transition from short- to long- term. We examined how women’s mate preferences changed over the development of a relationship, to see if they varied consistently with what is known about variation in men’s mating effort. Vignettes detailed four key milestones in the development of a relationship and women rated the importance of the man at each stage displaying indicators of mating or parenting effort. Women increasingly prioritised indicators of parenting effort in men as the relationship developed, consistent with what is known about men’s reduction in mating effort in favour of parenting effort over the development of a relationship. The results support predictions from Life History Theory and highlight the interacting mutually reinforcing nature of sexually selected behaviours

SHUBNIKOV-DEHAAS OSCILLATIONS ON AS-GROWN AND ANNEALED MOLECULAR-BEAM-EPITAXY-GROWN HG1-XCDXTE ALLOYS DOPED WITH INDIUM

Transverse resistivity rho(xx), longitudinal resistivity rho(zz), and Hall resistivity rho(xy) on heavily indium-doped as-grown and annealed Hg1-xCdxTe (0.24 < x < 34) alloys in a magnetic field up to 12 T and temperature range 1.2-25 K have been measured. The as-grown and annealed samples show good quality Shubnikov-de Haas oscillations in which the effective masses m{*}, free-electron densities n(SdH), and Dingle temperatures T(D) are extracted. The deduced m{*} and n(SdH) from the as-grown and annealed samples are in good agreement within 12%. However, there are considerable improvements in the low field Hall mobility mu(H) (a maximum 54% increase) and a reduction in T(D) (a maximum 65% decline) in the annealed samples. Analysis at low field seems to indicate that broadening due to an inhomogeneous impurity distribution contributes to T(D) in addition to the partial cancellation produced by different frequencies of oscillations. An estimate of the average values of an electron density fluctuation DELTAn/n and its spatial extent DELTAL based only on T(D) and Hall mobility temperature T(mu) is presented. The deduced DELTAL is in the order of mean free path l. This, therefore, can limit mu(H) and the values of l and DELTAL and this indicates that if there is an inhomogeneous distribution of indium donor, high-temperature annealing tends to homogenize the distribution of indium donors by diffusion

Band offset and lattice mismatch effects in strained-layer CdTe-ZnTe superlattices.

International audienceWe present a detailed investigation of the combined effects of band offsets and lattice mismatch on the subband structure of strained-layer CdTe/ZnTe superlattices. It is shown that, depending on the layer thicknesses, the superlattice may either have a type-I configuration, where electron and hole are mostly localized within CdTe layers, or a type-II configuration. Moreover, the hole ground state may either be the heavy-hole subband or the light-hole one. The results are compared with photoluminescence data and the value ΔEv=60±20 meV is obtained for the zero-strain valence-band offset

Ammoniation of straw by urea: extent of ureolysis and improvement of nutritive value with moderate water addition

International audienc