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A Se chemical passivation [(NH4)2S+Se] for GaAs Schottky diodes is presented. We have found that our (NH4)2S+Se passivated Schottky diodes have more than one order of magnitude higher forward current density than the (NH4)2Sx passivated ones. In rapid thermal annealing treatment, an initial decrease and then increase of forward current density for (NH4)2Sx passivated diodes is observed. For the (NH4)2S+Se and (NH4)OH treated diodes, a steady decrease of Schottky barrier height with increased annealing temperature is observed. With or without annealing treatment, the (NH4)2S+Se passivated diodes have the lowest barrier height.

Pulse-Doppler radars require high-computing power. A massively parallel machine has been developed in this paper to implement a Pulse-Doppler radar signal processing chain in real-time fashion. The proposed machine consists of two C6678 digital signal processors (DSPs), each with eight DSP cores, interconnected with Serial RapidIO (SRIO) bus. In this study, each individual core is considered as the basic processing element; hence, the proposed parallel machine contains 16 processing elements. A straightforward model has been adopted to distribute the Pulse-Doppler radar signal processing chain. This model provides low latency, but communication inefficiency limits system performance. This paper proposes several optimizations that greatly reduce the inter-processor communication in a straightforward model and improves the parallel efficiency of the system. A use case of the Pulse-Doppler radar signal processing chain has been used to illustrate and validate the concept of the proposed mapping model. Experimental results show that the parallel efficiency of the proposed parallel machine is about 90%.

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