We have designed and fabricated terahertz quantum cascade lasers (THz QCLs) with double metal waveguide (DMW) based on three and four-quantum well GaAs/Al0.15Ga0.85As active module with resonant-phonon depopulation scheme. Three-well and four-well THz QCLs have a lasing frequencies of 3.2 THz and 2.3 THz, respectively. We investigate the dependence of threshold current and lasing output power on temperature for fabricated THz QCL. We propose to use DMW based on silver (Ag) for reducing the losses of the waveguide. The spectra of the loss coefficient of the DMW based on Au and Ag are calculated. It is shown, that the use of Ag-based DMW allows to reduce losses by 2-4 cm–1 in comparison with Au-based DMW. Taking into account the absorption of THz radiation by free carriers and optical phonons, the spectrum of total mode losses has a wide minimum in the region of 3-6 THz, which shifts to the highfrequency region of the spectrum with increasing temperature. The postgrowth processing for THz QCL with Ag-Ag DMW are studied.
Paper presents the results of research of electrical characteristics features of multibarrier AlxGa1-xAs/GaAs heterostructures with tunnel-nontransparent potential barriers. Briefly described constructive-technological features fabricated using molecular beam epitaxy. We measured the quasi-static current-voltage characteristics of test items by electric pulses of duration 10-6 s and a duty cycle of 103. Observed characteristics with a strong section of the negative differential resistance in the current range of several tens of milliampers. It is proposed to use this effect for the generation of terahertz electromagnetic radiation. Briefly stated the theoretical interpretation of the observed phenomena on the basis of quasi-hydrodynamic theory of electron drift.
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