On low-frequency noise of polycrystalline GexSi1−x for sub-micron CMOS technologies

Polycrystalline gate films of GexSi1−x were deposited using low pressure chemical vapor deposition. To study the effects of different Ge contents on the noise properties, a value x=0, 0.3, and 0.6 was selected. Samples of 300 and 500 nm thickness were prepared for comparing the thickness effects on the quality of the gate films. The gate films were implanted with different concentrations of boron. The morphology and electrical properties have been characterized using atomic force microscopy, transmission electron microscopy, and Hall-effect measurements. Conductance fluctuations were measured at room temperature. We present here how low-frequency noise depends on the Ge contents, the doping concentration, and on the thickness of the gate film. The 1/f noise in polycrystalline GexSi1−x can be analyzed in terms of mobility fluctuations caused by lattice scattering.