Ion-cleaning damage in (100) GaAs,and its effect on schottky diodes

This study investigates the effect of ion cleaning damage of (100) GaAs in the 100–1000 eV range, and also its recovery with thermal annealing to 400°C. It is shown that GaAs could be annealed to a considerable extent if the ion-damage was ? 100 eV. However, full recovery was not achieved. On the other hand, samples damaged at ? 400 eV became progressively worse with annealing. Measurements indicate that these samples are dominated by the effect of arsenic variances within the bulk. These remain in the bulk, but are distributed spatially upon annealing. They behave as deep donors, so that the net electron concentration in the bulk is enhanced. Aluminum-n GaAs Schottky diodes were used as a vehicle for this study.     

Advances in Digital Radio Systems

This paper examines the analog methods presently used in carrying digital signal via the terrestrial microwave radio relay systems. It then summarized the state of the art of two proposed digital radio systems, operating above and below 10 GHz. It also highlights some of the problem areas yet to be solved, with particular emphasis on these design problems associated with the high-capacity system. An extensive bibliography is given for easy reference.     

Nano-Wear Mechanism for Ultra-High Molecular Weight Polyethylene (UHMWPE) Sliding Against a Model Hard Asperity

This paper investigates the mechanism of wear-particle generation when a single asperity is passed over the surface of UHMWPE. A single asperity is modelled using a conical diamond-tip indenter attached to a nano-scratch tester. Scratches are produced by passing the indenter over the surface of the polymer in a single pass and multiple passes on a single track or on orthogonally intersecting tracks. The debris-generation process, as observed in the nano-scratch test, is complex and depends upon the direction of scratches. It is found that the rate of wear-debris generation is much higher when two consecutive scratches orthogonally intersect each other compared to when the scratches are made on the same track. Wall formation was observed between orthogonally intersecting scratches, and it is believed that this is central to the low-cycle wear mechanism in these systems.     

High-transfer-rate high-capacity holographic disk data-storage system

We describe the design and implementation of a high-data-rate high-capacity digital holographic storage disk system. Various system design trade-offs that affect density and data-rate performance are described and analyzed. In the demonstration system that we describe, high-density holographic recording is achieved by use of high-resolution short-focal-length optics and correlation shift multiplexing in photopolymer disk media. Holographic channel decoding at a 1-Gbit/s data rate is performed by custom-built electronic hardware. A benchmark sustained optical data-transfer rate of 10 Gbits/s has been successfully demonstrated.