F. Goschenhofer's research while affiliated with University of Wuerzburg and other places

Publications (10)

Article
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It has been demonstrated that two closely spaced peaks in the infrared absorption spectra of several HgTe/Hg1-xCdxTe(112)B superlattices (SL's) are due to the H1-E1 intersubband transition at the center of the Brillouin zone and the zone boundary. The miniband width agrees well with (8×8k•p) calculations. The intersubband transition energies of SL'...
Article
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We report results of high-resolution electron energy-loss measurements in transmission of CdTe films. In contrast to simple metals and other semiconductors studied experimentally so far, our results show a number of loss structures of comparable strength occupying a rather narrow energy region around the classical plasmon energy. With increasing mo...
Article
We report on experimental and theoretical investigations of the cyclotron mass in six n-type modulation doped HgTe single quantum wells. Magnetotransport measurements at low temperatures resulted in well pronounced Shubnikov–de Haas oscillations and quantum Hall plateaus. The cyclotron mass was determined from the temperature dependence of the Shub...
Article
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N-type Hg1−xCdxTe layers with x values of 0.3 and 0.7 have been grown by molecular beam epitaxy using iodine in the form of CdI2 as a dopant. Carrier concentrations up to 1.1 1018 cm−3 have been achieved for x = 0.7 and up to 7.6 1017 cm−3 for x=0.3. The best low temperature mobilities are 460 cm2/(Vs) and 1.2 105 cm2/(Vs) for x=0.7 and x=0.3, resp...
Article
Full-text available
The temperature dependence of the energy gap of zinc‐blende CdSe and Cd 1-x Zn x Se has been determined over the entire range of composition from optical transmission and reflection measurements at temperatures between 5 and 300 K. The experimental results can be expressed by the following modified empirical Varshni formula, whose parameters are fu...
Article
Full-text available
The temperature dependence of the energy gap of zinc-blende CdSe and Cd 1x Zn x Se has been determined over the entire range of composition from optical transmission and reflection measurements at temperatures between 5 and 300 K. The experimental results can be expressed by the following modified empirical Varshni formula, whose parameters are fun...
Article
The experimental optical absorption coefficient of HgTe/Hg(subscript 0.32)Cd(subscript 0.68)Te superlattices with a wide range of well and barrier widths have been compared with theoretical calculations. There is good agreement with experiment if the Cd concentration profile across the as-grown interfaces is assumed to have the shape given by an er...
Article
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We report here on infrared magneto-optical studies of band gaps and electron cyclotron resonances of a narrow-gap HgTe-Hg1-xCdxTe superlattice. The experimental electron effective mass at the conduction-band edge and four different interband transition energies are compared to the prediction of a 8×8 k.p band-structure calculation in order to deter...
Article
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The optical properties of HgSe grown by molecular-beam epitaxy have been studied over a wide range of frequencies covering the E0, E1, and E1+Delta1 gaps. Theoretical calculations of the dielectric function are used in deriving fundamental material parameters for HgSe. The refractive index has thus been determined at room temperature up to 1 eV. A...
Article
Full-text available
The molecular beam epitaxially growth of (001) Hg1-xCdxTe-HgTe superlattices has been systematically investigated. The well width as well as the period were determined directly by X-ray diffraction. This was accomplished for the well width by exploiting the high reflectivity from HgTe and the low reflectivity from CdTe for the (002) Bragg reflectio...

Citations

... The induced changes were not very reproducible, however. More promising is the use of modulation doping layers [87] which induce a constant density shift. This approach allows for high quality QHE measurements in HgTe 3D TI devices up to high magnetic fields (cf. ...
... Commonly used characterization techniques are often challenging for HgCdTe. In particular, there are not many papers on transmission electron microscopy of HgCdTe heterostructures [19,20], and the photoluminescence (PL) studies of HgCdTe in the very long wavelength range are also quite scarce [21,22]. Complications in PL studies are related to low efficiency of light emission and less sensitive detectors in the long wavelength region. ...
... The plasmon energy shifts will be related to the unit-cell volume changes and thus to the alloy strain, as discussed next. GaAs exhibits one major plasmon peak at~16 eV, and unlike, e.g., CdTe, it does not show complex interfering features from inter-band transitions [55]. As a first approximation to interpret the measured plasmon energy changes, we employ the Drude-Lorenz model for free-electron electron gas, where free electrons are now the valence electrons in the semiconductor [56]. ...
... The importance of the experimental determination of the effective mass and g-factor in systems with a sophisticated dispersion law, to which the structures based on HgTe belong, is beyond doubt. The previously obtained experimental values of the g-factor and effective mass for HgTe quantum wells are contradictory and depend on the width of the quantum well and the electron density [39][40][41][42][43][44][45][46]. It was previously noted [39][40][41][42] that there is a problem of accordance between theoretical and experimental estimates of the effective mass in such QWs. ...
... When comparing temperature dependence of maximum emission energy for NBP:CdSe/ZnS(0.3) and NBP:CdTe composites with bandgap energy of bulk CdSe [19] and CdTe [20] (Figure 5), it can be noticed that in the case of both QD-doped materials it changes with increasing temperature faster than bandgap energy of a bulk semiconductor. It indicates that the emission originates from a quantum structure rather than from a solid material, that would be created if the QDs had melted into the glass matrix. ...
... The Debye temperature is a useful parameter in understanding the various solid-state physics because of its inherent relationship to lattice vibrations. If θ D,0 in Eq. (22) is not strongly dependent on T, the temperature dependence of I PL comes only from the thermal quenching defined by E q in Fig. 7 [see also Eq. (22)]. It has been reported that the Deby temperature θ D of a semiconductor or an insulator has a generalized relationship with the lattice parameter, namely, the larger the lattice parameter, the smaller is the Debye temperature θ D [18]. ...
... The observed magneto-optical response − due to intraband (cyclotron resonance) and interband inter-Landau level excitations − may be interpreted in the context of previous studies performed on bulk samples [19][20][21][22], quantum wells [23][24][25][26][27][28][29][30][31][32][33] and superlattices [34][35][36][37][38][39][40][41], but also compared with theoretical expectations. Here we aim at achieving the quantitative explanation of the collected experimental data, but also further developing a reliable theoretical model. ...