Microwave noise measurements on Al0.3Ga0.7As/GaAs channels grown by molecular beam epitaxy using As2 and As4

We present microwave noise measurements performed on different high electron mobility transistor channels under both darkness and illumination. Two structures of Alo(0.3)Gao(0.7)As/GaAs layers have been grown with beams of Asp and As-4 using molecular beam epitaxy. The measured room temperature, Hall mobilities and sheet carrier densities have demonstrated in both cases a good de performance of the channels. However, the measurement of the noise temperature at 1.5 GHz has shown the sample grown with As-4 to be considerably noisier than the one grown with AS(4).