Complementary GaAs SIS FET inverter using selective crystal regrowth technique by MBE
A first complementary GaAs semiconductor-insulator-semiconductor (SIS) FET inverter has been fabricated by constructing n-channel and p-channel GaAs SIS FET's on a single LEC GaAs substrate using MBE selective crystal regrowth technique. The fabricated inverter shows an inverter operation as a really low-power complementary inverter.
p-channel quantum-well heterostructure MI/sup 3/SFET
A p-channel heterostructure MISFET-like device based on a quantum well with an underlying impurity layer is discussed. The device is based on an AlGaAs/GaAs heterostructure with a recessed-gate geometry and uses Zn-diffused refractory-metal contacts. The 4100 cm/sup 2//V-s hole mobility obtained in this inverted-interface structure at 77 K is comparable to that achieved in normal-interface AlGaAs/GaAs heterostructures. Transconductance and K-factor values as high as 52 mS/mm and 140 mS/V-mm, respectively, are obtained at 77 K in p-channel FETs with 2.0- mu m gate lengths and 6.0- mu m source-drain spacings, representing state-of-the-art values for p-HFETs at similar dimensions.<<ETX>>
Palm oil shell aggregate for lightweight concrete
Publisher Summary Increased agricultural production and the development of agro-based industries in many countries of the world have brought about the production of large quantities of agricultural wastes, most of which are not adequately managed and utilized. Low-cost building materials can be produced using inexpensive indigenous raw materials. Agricultural wastes that are renewable and are found in abundance in many countries present an interesting alternative to the traditional and sometimes imported building materials, particularly for low-cost construction. The use of agricultural wastes as aggregates in lightweight concrete can provides an alternative to conventional methods for the production of lightweight concrete. Lightweight concrete results in a reduction in the overall deadweight of a structure and provides a significant saving in the overall cost of construction. The use of less expensive alternative lightweight aggregates in the production of the concrete can provide further reductions in expense. The material properties and structural performance of lightweight concrete with palm oil shells as aggregates are similar to lightweight concrete produced using the more common lightweight aggregates such as clinker, foamed slag, and expanded clay. The palm oil shells are hard and are received as crushed pieces because of the process used to release the oil. Manual sieving is necessary to remove the large amount of fine particles. The shells are then air-dried before use. Because the palm oil shells are lighter than the cement matrix, the shells tend to segregate in wet concrete mixes. On the other hand, dry mixes using palm oil shells are relatively more difficult to work with when compared to ordinary concrete. Trial mixes are necessary to achieve a good mix design.