CONDUTIVIDADE INDUZIDA POR LUZ EM Al x Ga 1-x As - EFEITOS DEVIDO À VARIAÇÃO DE TEMPERATURA

Abstract

There are temperature ranges where photoconductivity spectra are completely masked by deep levels, such as DX centers which is dominant in AlxGa1-xAs. We have measured photoconductivity spectra as function of temperature and have found that above approximately 120K, the absence of persistent photoconductivity contributes for a very clean photoconductivity spectrum, and the bandgap transition is easily evaluated. We have also measured resistance as function of temperature under influence of steady illumination of monochromatic light in the range 0,5-1,5µm, and plot the conductance (GxT). Below 70K, GxT behavior depends on the aluminum amount in the composition, since in direct bandgap samples, above bandgap light increases conductivity to higher values than at room temperature and below bandgap light is not enough to avoid trapping by another level.