1/F NOISE AND GENERATION RECOMBINATION PROCESSES AT DISCRETE LEVELS IN SEMICONDUCTORS

The effect of correlation between the level of 1/f noise and the low-frequency generation-recombination (GR) plateau in the noise spectrum of different semiconductors and devices is described and investigated. It is shown that alpha-H approximately tau for conductivity noise where alpha-H is Hooge's coefficient and tau is the relaxation time for the "noisy" GR process. The value of tau has been changed by varying the sample thickness or its temperature and by applying to it not only the eletric field but also the crossed magnetic and electric fields. The resulting values of tau appear to be connected with different centers and processes (trapping, recombination, diffusion) which occur in different regions (volume, surface) of the sample. It is shown also that S(U)1/f approximately tau for the equivalent gate voltage fluctuations in JFETs, where S(U)1/f corresponds to the 1/f region of the spectrum of these fluctuations and tau is determined from the GR region of this spectrum, both values depending on temperature and gate voltage. In this case the values of tau appear to be connected with the trapping processes at two different levels in the gate region. An analysis of these data shows that 1/f noise investigated may result from processes caused by capture and release of charge carriers at one discrete level. The possible role of lattice relaxation phenomena is discussed.