Background. The problem of development of the terahertz range with solid state devices remains relevant today. Gunn diodes, IMPATT diodes, resonant tunneling diodes and others are used as active elements. At frequencies above 100 GHz, these devices have a number of physical problems that limit maximum operation from above. One of the possibilities of creating high-frequency Gunn diodes is the use of various graded-gap multicomponent semiconductor compounds. Gunn diodes based on such compounds have higher generation efficiency and, accordingly, output power.
Objectives. Multicomponent semiconductors, the fractional composition of which varies in space, can improve the interaction of the electric field and electrons in devices operating on the effect of intervalley electron transfer. To achieve the best effect, such a semiconductor should have an optimal coordinate dependence between the nonequivalent valleys of the conduction band. Therefore, the aim of the work is to investigate the dependences of the effective generation of current oscillations in the terahertz range based on a graded-gap semiconductor Ga1-x(z)Iny(z)Py(z)As1-y(z).
Materials and methods. Using mathematical modeling n+ - n - n+ Gunn diodes based on a graded-gap semiconductor Ga1-x(z)Iny(z)Py(z)As1-y(z) with active region length being 1,0 µm and the concentration of ionized impurities in it being 9×1016 cm–3 are considered. The study was carried out based on the solving Boltzmann kinetic equation for a three-level Г–L–X model of intervalley electron transfer. The resulting system of equations is solved numerically and allows one to get the dynamic distribution of the concentration of charge carriers, their energy, current density, electric field strength, and the voltage drop across the diode.
Results. It is shown that in graded-gap diodes based on Ga1-x(z)Iny(z)Py(z)As1-y(z) some domain current instability mode can be implemented. Unlike similar devices based on homogeneous semiconductors, such as GaAs, InP or Ga0,5In0,5As, in diodes based on graded-gap Ga1-x(z)Iny(z)Py(z)As1-y(z) undamped current oscillations occur. The maximum power of the main mode of such oscillations is 19 mW at a frequency of 95 GHz. Higher harmonics are present in the oscillations spectrum: the power of the second harmonic is 1,6 mW, and that of the third is 0,3 mW. The frequency and power of self-oscillations in graded-gap diodes depends on the composition of the semiconductor compound both in the anode and in the cathode and is observed at optimal values of the applied voltage.
Conclusions. Graded-gap Gunn diodes based on Ga1-x(z)Iny(z)Py(z)As1-y(z) with active region length being 1,0 µm and the concentration of ionized impurities in it being 9×1016 cm–3 are able to generate continuous current oscillations in a fairly wide frequency range due to efficient operation at the main, second and third harmonics. The research results can be used in the development of high-frequency devices for various scientific research.
