The 1/f noise of InP based 2DEG devices and its dependence on mobility

The 1/f noise of various InP-based two-dimensional electron gas (2DEG) structures with InGaAs channels was investigated at room temperature in the frequency range from 0.4 Hz to 100 kHz. The experimental results on the gate-bias dependent 1/f noise in MBE-grown InAlAs/InGaAs/InP heterostructure field-effect transistors (HFET's) biased in the ohmic region were interpreted in the framework of a model which considers a separation of the HFET into a parasitic and the gated channel region. The results reveal a significant dependence of the Hooge parameter /spl alpha//sub Hg/ of the gated channel region on the bias dependent mobility /spl mu//sub g/. The assumed inverse proportionality between /spl alpha//sub Hg/ and /spl mu//sub g/ due to Coulomb interactions near pinchoff allows an exact description of the noise behavior in the whole bias range. Additionally, the 1/f noise in ungated 2DEG structures of three different MOCVD-grown Al-free and five different MBE-grown Al-containing InP-based heterostructures with InGaAs channels was investigated with respect to the channel design. In spite of various channel designs with mobilities between 6470 cm/sup 2//Vs and 11 500 cm/sup 2//Vs, the Hooge parameter of all devices showed a clear dependence on mobility (/spl alpha//sub H//spl sim//spl mu//sup -2.6/). The lowest observed Hooge parameter /spl alpha//sub H/=1.5/spl times/10/sup -5/ corresponding to the sample with the highest mobility was attributed to two-dimensional (2-D) phonon scattering processes.