S. V. Danylyuk

Double Injection Currents in p-i-n Diodes Incorporating Self-Assembled Quantum Dots

We study p-i-n diodes incorporating InAs/AlAs self-assembled quantum dots (QDs) to probe the electron and hole levels of the dots. A comparative analysis of capacitance-voltage, current-voltage and electroluminescence measurements shows that p-i-n structures could be successfully used as QD spectrometers.

The investigation of properties of electron transport in AlGaN/GaN heterostructures

Magnetoresistance of two-dimensional electron gas in the triangular quantum well created as a result of polarization effects at AlGaN/GaN heterointerface has been studied. Magnetotransport measurements clearly revealed Shubnikov-de Haas oscillations in both two terminal transmission line model samples and three terminal high electron mobility transistor structures at low temperature. Low value of quantum scattering time was obtained for different structures. Region with negative magnetoresistance was observed at low magnetic field.

Noise spectroscopy of AlGaN/GaN HEMT structures with long channels

In this paper we discuss the effect of dissipated power on the characteristic time of noise spectra transformation investigated in wide-bandgap AlGaN/GaN transistor structures with long channels. It is found that the characteristic time as a function of temperature demonstrates an exponential dependence with definite activation energy. Obtained results are explained based on the developed model of non-equilibrium fluctuations of the sample resistance. These fluctuations cause a local overheating due to local change of resistance. In the long channels these fluctuations may create overheating regions with two different self-heating temperatures, leading to different activation dependences, observed in the experiment.

Influence of Small Doses of Gamma Irradiation on Transport and Noise Properties of SiC MESFETs

Steady‐state characteristics and low‐frequency noise spectra of SiC‐based metal‐semiconductor field‐effect transistors (MESFETs) before and after small doses (1×106 rad) of gamma radiation treatment are studied. The structural ordering of non‐controllable impurities with radiation leads to an increase in threshold voltage, decrease of the channel’s resistance and reduces the number of G‐R components observed in the total noise spectra of the devices.

Low frequency noise parameters in an AlGaN/GaN heterostructure with 33% and 75% Al mole fraction

Transport and low frequency noise properties of undoped AlGaN/GaN high electron mobility transistor (HEMT) heterostructures with 33% and 75% Al mole fractions in the ohmic and nonlinear regimes of applied voltages are studied. In contrast to the low Al mole fraction, the noise properties of 75% content structures are not affected by passivation. At small voltages both kinds of structures demonstrate about the same level of 1/f excess noise. Deviations from conventional flicker noise were observed at high applied voltages. Additionally, differences in noise behaviour between the two structures were revealed. In the 75% content structures, a noise level suppression was registered in the non-linear regime, which is important for the development of low noise oscillator circuits.

Ultra-high electric field transport in GaN-based heterostructures

In this paper, we presented results of steady state and pulse measurement of AlGaN/GaN heterostructures up to ultra high electric fields accompanied by low frequency noise measurements. Hot electron relaxation process were analysed. The contact resistance was measured in low field (ohmic) region and taken into account when calculating the average electric field. The velocity-field characteristics in AlGaN/GaN heterostructures obtained by measurement of the current-voltage characteristics. The spectra of the normalised current noise for different values of electric field E measured at T=300 K for the device with channel length of 25 /spl mu/m and width of 100 /spl mu/m is studied through experimental results.