Electrical measurements during the thermal recovery of fast neutron irradiated GaAs confirm the main steps around 400 and 600 °C, corresponding to the decay of electron paramagnetic resonance identified V2−Ga and As4+Ga centers.
InGaAs epitaxial layers have been doped with beryllium with concentrations ranging from 1016 to 5×1019 cm−3 as measured by secondary ion mass spectroscopy (SIMS). From electrical measurements we have observed that p-type layers presented a high degree of compensation, and for a doping level below 5×10−7 cm−3, they are often found to be n type. SIMS analysis shows that oxygen is responsible for such behavior. Beryllium doping leads to incorporation of a large amount of oxygen in the epitaxial layers. Investigations on the origin of oxygen incorporation show that it is extremely sensitive to the residual vacuum during the growth and can be reduced by decreasing arsenic pressure.
To demonstrate the faisability of a new heterodyning process for a wind Lidar, we have, characterized Hg Cd Te photodetectors cooled at liquid nitrogen temperature, illuminated by two laser beams and pumped by an RF signal. Optical and microwave test bench and some experimental results are presented.INTRODUCTION:
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