The effect of the barrier width between coupled double quantum wells of GaAs/InGaAs/GaAs on the bipolar transport and THz emission of the hot carriers in the lateral electric field
M.M. Vinoslavskii, P.A. Belevskii, V.M. Poroshin, V.V. Vainberg
Institute of Physics of the National Academy of Sciences, 46 Nauki Ave., Kiev 03680, Ukraine
Научно-исследовательский физико-технический институт Нижегородского государственного университета им. Н.И. Лобачевского, г. Нижний Новгород, 603950, Россия
Received November 13, 2019, published online April 24, 2020
The dependences of the current and integral intraband terahertz electroluminescence on the electric field in the heterostruc-tures of n-InGaAs/GaAs with the asymmetric double tunnel-coupled quantum wells under the conditions of the bipolar lateral transport are established to differ qualitatively for different barri-er widths between wells. In the case of the thick (~50 Å) barriers at the electric fields less than those corresponding to Gunn kind instability one observes the high-frequency current oscillations and the emission intensity monotonously increasing with increasing electric field in the whole range up to 3 kV/cm. At small barrier widths (~30 Å) the current oscillations are practically absent and the emission intensity strongly increases with the field at the strengths higher than 1,5 through 2 kV/cm. The emission intensity growth is explained by the addition of the direct transitions of the electrons and holes between the size quantization subbands to the indirect optical intrasubband transitions. The observed differences are shown to may be explained by the difference in the ratio of the time of interband radiative recombination of the minority charge carriers, holes, in the narrow wells and the time of the holes tunneling into the wide wells, which depends on the barrier width between the wells.
Key words: heterostructures, lateral transport, real-space transfer, terahertz radiation, current instabilities, tunneling time.