The trace of the gate noise voltage was successfully caught by the measurements of the correlation between the noise outputs of a pair of JFETs connected to a common gate resistor. It is shown for 2SK150 (n-channel junction FET) that the gate noise voltage is 1/f-type and its level is -142dbV2/Hz at 1Hz, and that the correlation coefficient between the gate noise voltage and the gate noise current is -1.
The Hooge parameters of compound semiconductors are found to be in inverse proportional to the mean free paths of materials. The newly developed model of 1/f phonon energy partition fluctuation in thermal equilibrium predicts the value of Hooge parameter as αH = a/λ, the ratio of the lattice constant a and the mean free path λ. Several reported experimental results on αH for very pure semiconductors are found on the a/λ line. Experimental verification is given by measuring noise in InGaAs/InAlAs heterostructure, where optical phonon effects can be observed due to negligible impurity scattering. The Hooge parameter of about 1 in p-InGaAs and 10-3 to 10-5 in n-InGaAs reflects the two order difference in the mobility and corresponding λ values.
In the present paper, emphasis is laid on those RTS showing a capture process, which deviates from the standard Shockley-Read-Hall kinetics. A modified two-step approach is proposed. In this case the charge carrier quantum transitions represent a primary process X(t), which involves two or three quantum states. The measurable quantity is the current modulation, which has discrete states, too. The current modulation is then represented by a secondary process Y(t). The proposed model can explain some of the complex switching phenomena being measured in nanoscale devices. The quadratic dependence of the capture rate on the current and the noise spectral density dependence on the current and temperature are analysed. It is shown that the occupation time probability density for emission is given by a superposition of two exponential dependencies, whereas the capture time constant distribution is purely exponential.
We have fabricated ultrafast electrical waveguides with low-k polyimide integrated with ultrafast photoconductive switches formed by nano-anodization process for the first time. Electrical signals are affected by nonlinear capacitance of p-n junctions in this waveguides, and pass through the low-k polyimide, so the dielectric loss and the radiation loss are dramatically reduced. The electrical pulses as short as 290 fs were measured on this waveguide by an electro-optic sampling system based on a femtosecond laser.