Coherent Phonon Dynamics in Short-Period InAs/GaSb Superlattices

We have performed ultrafast pump-probe spectroscopy studies on a series of InAs/GaSb-based short-period superlattice (SL) samples with periods ranging from 46 \AA to 71 \AA. We observe two types of oscillations in the differential reflectivity with fast ($\sim$ 1- 2 ps) and slow ($\sim$ 24 ps) periods. The period of the fast oscillations changes with the SL period and can be explained as coherent acoustic phonons generated from carriers photoexcited within the SL. This mode provides an accurate method for determining the SL period and assessing interface quality. The period of the slow mode depends on the wavelength of the probe pulse and can be understood as a propagating coherent phonon wavepacket modulating the reflectivity of the probe pulse as it travels from the surface into the sample.Comment: 6 pages, 4 figure

Impact of growth temperature on InAs/GaInSb strained layer superlattices for very long wavelength infrared detection

We explore the optimum growth space for a 47.0A ° InAs/21.5A ° Ga0.75In0.25Sb superlattices (SLs) designed for the maximum Auger suppression for a very long wavelength infrared gap. Our growth process produces a consistent gap of 5065meV. However, SL quality is sensitive to the growth temperature (Tg). For the SLs grown at 390 470 C, a photoresponse signal gradually increases as Tg increases from 400 to 440 C. Outside this temperature window, the SL quality deteriorates very rapidly. All SLs were n-type with mobility of 10 000 V/cm2 and 300K recombination lifetime of 70 ns for an optimized SL

The impact of employment equity regulations on psychological contracts in South Africa

This article will show the impact of employment equity legislation on the psychological employment contracts of the three main employee groupings in South African society. This study is important in that it fills the gap in the literature that identifies labour market regulations as an important shaping influence on the psychological contract. More than 500 managers from across South African industry and from all ethnic groups were surveyed to identify differences in psychological contracts and attitudes towards the social transformation regulations. We found that the legislation has impacted differentially on the three groupings mainly in terms of their loyalty to stay with their organizations, the focus on their career development in terms of the external labour market and the degree to which they felt they had been affected by the legislation. Additionally we find that the perceived linkage between job satisfaction and labour turnover is significantly weakened by labour market legislation in the case of the beneficiaries of the legislation, but that this may not be the case for those negatively affected by the legislation. The findings have significant implications for the HRM practices of multinationals operating in societies with significant labour market regulatory interventions