Design of lumped element quadrature hybrid

Y.C. Chiang, C.Y. Chen
1998 Electronics Letters  
methan and hydrogen was used. Secondly, the cleaning step is the result of several contamination investigations. For a clear insight into the efficiency of our cleaning procedure, atomic force microscope (AFM) measurements were performed just after epitaxy (Fig. 2) . A comparison with AFM measurements obtained on the same wafer when processed as described above is reported in Fig. 3 . Note that the surface morphology before and after technology is the same on a nanometer depth scale and reveals
more » ... h scale and reveals the terraces formed on epitaxial materials. Moreover, X-ray photoelecton spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) measurements confirmed these results and have shown that oxygen and carbon contamination were very low, being reduced to the dose corresponding to natural contamination. Acknowledgments: We would like to thank L. Row for helping in measurements and M.P. Besland from Ecole Centrale de Lyon for having contributed to XPS measurements. 0 IEE 1998
doi:10.1049/el:19980361 fatcat:k2jgh6saurbghe5hkyqkouk7o4