Noise in p-channel SiGe and Si MOSFETs with gate oxide grown by low temperature plasma anodisation

A study is made of noise in p-channel MOS transistors incorporating SiGe surface and buried channels and in p-channel Si MOS transistors, over the frequency range f=1 Hz to 100 kHz. The gate oxide is grown by low temperature plasma anodisation. The devices exhibit only 1/f noise. It is found that in most cases this noise is due to fluctuations of charge in slow oxide traps while the Hooge 1/f noise is also detected in some buried channel SiGe devices. The noise analysis shows that the buried p-channel SiGe and Si control devices exhibit quite low and similar slow state densities of the order of 10¹⁰ cm^-2 eV^-1 whereas the surface channel devices show much higher slow state density (~10¹¹ cm^-2 eV^-1)