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Gershenzon EM, Gol'tsman GN, Multanovskii VV, Ptitsyna NG. Capture of photoexcited carriers by shallow impurity centers in germanium. Sov Phys JETP. 1979;50(4):728–34.
Abstract: Measurements were made of the lifetimes rf of free carriers and the relaxation time 7, of the submillimeter impurity photoconductivity when carriers are captured by attracting shallow donors and acceptom in Ge. It is nod that in samples with capture-center concentration N,Z 10"cm-' the relaxation time 7, greatly exceeds rf in the temperature range 4.2-12 K. The measured values of 7,- are compared with the calculation of cascade recombination by the classical model. To evaluate the data on T,, the distinguishing features of this model are considered for the nonstationary case. The substantial difference betweea the values of rf and T, is attributed to re-emission of the carriers from the excited states of the shallow impurities.
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Gershenzon EM, Gol'tsman GN, Kagane ML. Observation of free carrier resonances in p-type germanium at submillimeter wavelengths. Sov Phys Solid State. 1978;20(4):573–9.
Abstract: The spectrum of hole resonances in pure p-Ge for submillimetre in quantizing magnetic fields has been studied and identified. Measurements of photoconductivity spectra of p-Ge were made in the wave range lambda = 2-0.3 mm at temp. of 4.2-15 deg K in magnetic fields H up to 40 Measurements at various frequencies showed that the position of a series of characteristic resonances depends on the frequency of the illumination. This is in line with theoretical conclusions about the effective mass of the carriers increasing with rise in the magnetic field as a result of the interaction of the edge of the valency band with the split spin-orbital interaction of the sub 7 exp + band and the conduction band. The relative intensity of the quantum resonance lines of the free holes depends on the excitation conditions.
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Gershenzon EM, Gol'tsman GN, Kagane ML. Energy spectrum of acceptors in germanium and its response to a magnetic field. Sov Phys JETP. 1977;45(4):769–76.
Abstract: We investigated the spectrum of the submillimeter photoconductivity of p-Ge at helium temperatures and the effects of a magnetic field up to 40 kOe on the spectrum. A large number of lines of transitions between the excited states of the acceptors was observed, some of the lines were identified, and the energies of a number of spectral levels B, Al, Ga, In, and TI in Ge were identified. The results are compared with calculations and with experimental data obtained from the spectra of the photoexcitation of the ground state of the impurities. Using one transition as an example, we discuss the splitting of the excited states of acceptors in the magnetic field and under uniaxial compression.
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Semenov A, Engel A, Il'in K, Gol'tsman G, Siegel M, Hübers H-W. Ultimate performance of a superconducting quantum detector. Eur Phys J Appl Phys. 2003;21(3):171–8.
Abstract: We analyze the ultimate performance of a superconducting quantum detector in order to meet requirements for applications in near-infrared astronomy and X-ray spectroscopy. The detector exploits a combined detection mechanism, in which avalanche quasiparticle multiplication and the supercurrent jointly produce a voltage response to a single absorbed photon via successive formation of a photon-induced and a current-induced normal hotspot in a narrow superconducting strip. The response time of the detector should increase with the photon energy providing energy resolution. Depending on the superconducting material and operation conditions, the cut-off wavelength for the single-photon detection regime varies from infrared waves to visible light. We simulated the performance of the background-limited infrared direct detector and X-ray photon counter utilizing the above mechanism. Low dark count rate and intrinsic low-frequency cut-off allow for realizing a background limited noise equivalent power of 10−20 W Hz−1/2 for a far-infrared direct detector exposed to 4-K background radiation. At low temperatures, the intrinsic response time of the counter is rather determined by diffusion of nonequilibrium electrons than by the rate of energy transfer to phonons. Therefore, thermal fluctuations do not hamper energy resolution of the X-ray photon counter that should be better than 10−3 for 6-keV photons. Comparison of new data obtained with a Nb based detector and previously reported results on NbN quantum detectors support our estimates of ultimate detector performance.
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Ozhegov RV, Gorshkov KN, Gol'tsman GN, Kinev NV, Koshelets VP. The stability of a terahertz receiver based on a superconducting integrated receiver. Supercond Sci Technol. 2011;24(3):035003.
Abstract: We present the results of stability testing of a terahertz radiometer based on a superconducting receiver with a SIS tunnel junction as the mixer and a flux-flow oscillator as the local oscillator. In the continuum mode, the receiver with a noise temperature of 95 K at 510 GHz measured over the intermediate frequency (IF) passband of 4-8 GHz offered a noise equivalent temperature difference of 10 ± 1 mK at an integration time of 1 s. We offer a method to significantly increase the integration time without the use of complex measurement equipment. The receiver observed a strong signal over a final detection bandwidth of 4 GHz and offered an Allan time of 5 s.
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