LOW-FREQUENCY NOISE AS A CHARACTERIZATION TOOL FOR INP-BASED AND GAAS-BASED DOUBLE-BARRIER RESONANT-TUNNELING DIODES

This paper describes the application of low frequency noise measurements to study impurity states in three types of double-barrier resonant tunnelling diode (RTD). The noise in two types of RTD could be modelled as a combination of 1/f and generation-recombination (G-R) components, in which the G-R noise displays characteristic shoulders in the noise spectra, owing to its lorentzian nature, and in which each shoulder has an associated amplitude A and comer frequency f(C). Using G-R theory, we can derive the relationship ln(tauT2)=(E(A)/k).(1/T)-ln(Bsigma), which relates the comer frequencies of the lorentzian relationships at several temperatures to the activation energy E(A) and the capture cross-section sigma of the trap or impurity state. Therefore, by plotting ln(tauT2) vs. 1/T, E(A) can be calculated from the slope and sigma from the y intercept. For example, for the GaAs-based RTD, two traps with EA values of 135 and 200 meV, with corresponding sigma values of 4 x 10(-16) CM2 and 1.1 x 10(-17) CM2, were determined from noise measurements between 300 and 77 K. The third type of RTD, which had excellent current-voltage characteristics, had a lower normalized current noise spectral density than those of the other two types of RTD, and the noise was predominantly of the 1/f type. Finally, some high temperature results (298-398 K) from InP-based RTDs, as well as an interpretation of the noise spectra will be presented.