Abstract-Suppressed Auger scattering and tunable light emission of Landau-quantized massless Kane electrons

D. B. But, M. Mittendorff, C. Consejo, F. Teppe, N. N. Mikhailov, S. A. Dvoretskii, C. Faugeras, S. Winnerl, M. Helm, W. Knap, M. Potemski & M. Orlita

https://www.nature.com/articles/s41566-019-0496-1

The Landau level laser was proposed long ago as a unique source of monochromatic radiation that would be widely tunable in the THz and infrared spectral ranges using a magnetic field. However, despite many efforts, this appealing concept never progressed to the design of a reliable device. This is because of the efficient Auger scattering of Landau-quantized electrons, an intrinsic non-radiative recombination channel that eventually gains over cyclotron emission in all materials studied so far (conventional semiconductors with parabolic bands, but also in graphene with massless electrons). Auger processes are favoured in these systems because the Landau levels (or their subsets) are equally spaced in energy. Here, we show that this scheme does not apply to massless Kane electrons in gapless HgCdTe, where undesirable Auger scattering is strongly suppressed and sizeable cyclotron emission is observed. The gapless HgCdTe thus appears as a material of choice for future Landau level lasers.

Abstract-Features of Photoluminescence of Double Acceptors in HgTe/CdHgTe Heterostructures with Quantum Wells in a Terahertz Range

D. V. Kozlov, V. V. Rumyantsev, A. M. Kadykov, M. A. Fadeev, N. S. Kulikov, V. V. Utochkin, N. N. Mikhailov, S. A. Dvoretskii, V. I. Gavrilenko, H.-W. Hubers, F. Teppe, S. V. Morozov,

https://link.springer.com/article/10.1134%2FS0021364019100114

The terahertz photoluminescence spectra of HgTe/CdHgTe heterostructure with quantum wells under interband optical excitation with a power of 3 to 300 mW have been studied in the temperature range of 30–100 K. The photoluminescence spectrum includes a band corresponding to quantum energies below the width of the band gap. The position of this band does not change with increasing temperature. This property allows attributing it to the capture of holes by acceptor centers. It has been shown that these acceptor centers are singly ionized mercury vacancies, which are double acceptors. A nonmonotonic dependence of the intensity of a signal of a long-wavelength photoluminescence band on the power of an exciting source has been revealed. A short-wavelength photoluminescence band corresponding to interband transitions appears with an increase in the exciting power. It has been shown that this effect is caused by the saturation of the number of partially ionized mercury vacancies with increasing pump intensity.