Gunn Diodes Based on Graded-gap GaInPAs

The problem of developing the terahertz range by active solid state devices remains relevant. High-speed transistors, Gunn diodes, IMPATT diodes, resonant-tunneling diodes and other devices are currently used to generate millimeter and sub-millimeter waves. However, at frequencies above 100-200 GHz, these devices have a number of physical problems that limit cut-off frequency. Nowadays, graded-gap semiconductors attract developers' interest as prospective materials for such devices, including those operating on the intervalley electron transfer effect. This paper presents the results of the numerical experiments on the current self-oscillation generation in the Gunn diodes based on graded-gap GaInPAs semiconductor alloy with the transit region length of 1.0 (m and concentration of ionized impurities therein of 9·1016 cm – 3. GaPAs – GaAs, GaInP – GaAs, GaPAs – InP, GaInP – InP, GaPAs – Ga0.5In0.5As and GaInP – Ga0.5In0.5As diodes have been studied. The numerical simulations have been carried out by means of the temperature model of intervalley transfer of electrons in the graded-gap semiconductors. In such diodes, the domain mode of current instability can be implemented and the continuous oscillations of the current occur, unlike homogeneous GaAs, InP, and Ga0.5In0.5As Gunn diodes, in which the continuous oscillations of the current don’t occur. The findings of the paper show that the graded-gap GaInPAs increase the oscillation power of the Gunn diodes in comparison with homogeneous GaAs, InP and Ga0.5In0.5As semiconductors, and self-oscillations contain clearly distinguishable at least third harmonic in the terahertz range. The maximum power of the fundamental mode is 19.4 mW at 98 GHz in Ga0.58In0.42P – Ga0.5In0.5As diode. Higher harmonics are present in the spectrum of oscillations with the power of the second harmonic of 1.0 mW and of the third harmonic of 0.2 mW.