Cyclotron resonance of the quasi-two-dimensional electron gas at Hg_1-xCd_xTe grain boundaries

Abstract

The magnetotransmission of a p-type Hg,,,,Cd,.,,,Te bicrystal containing a single grain boundary with an inversion layer has been investigated in the submillimetre wavelength range. For the first time t h e cyclotron resonance lines belonging to the various electric subbands of a quasi-two-dimensional carrier system at a grain boundary could be detected. The measured cyclotron masses and the subband densities determined from Shubnikov-de Haas experiments are compared with theoretical predictions and it is found that the data can be explained very well within the framework of a triangular well approximation model which allows for non-parabolic effects.

Evidence for semiconducting behavior with a narrow band gap of Bernal graphite

“…Of importance for understanding the measured behavior of the resistance of graphite samples is the existence of well-defined interfaces between the single-crystalline regions. As we mentioned in the introduction, interfaces between crystalline regions in semiconductors with different orientations, for example [20][21][22][23], lead to confined quasi-2D carrier systems with a much larger carrier density than the bulk matrix. We assume therefore that these interfaces running parallel to the graphene layers of the graphite structure are the origin of metalliclike resistivity as well as of the apparent large carrier density measured in bulk samples, i.e.…”

“…As the results from various semiconductors show (e.g. n-Ge bicrystals [20,21], p-InSb [22] as well as in Hg 1−x Cd x Te grain boundaries [23]), internal interfaces lead to the formation of confined quasi-2D carrier systems with n 0 ∼ 10 12 -10 13 cm −2 and clear signs of the quantum Hall effect [21]. Recent studies have demonstrated the large sensitivity of the resistivity of graphite samples to the internal interfaces that exist between crystalline regions of ∼30-100 nm thickness, a few microns long and running mostly parallel to the graphene planes [19].…”

Experimental Study of the Intrinsic and Extrinsic Transport Properties of Graphite and Multigraphene Samples

“…On the other hand it is well known that grain boundaries in various semiconductors can lead to the formation of quasi-two dimensional carrier systems confined in the boundaries. As early examples in literature we refer to the quasi-two dimensional electron gas system that was found at the inversion layers of n-Ge bicrystals (Uchida et al, 1983;Vul & Zavaritzkaya, 1979) or in p-InSb (Herrmann et al, 1984) as well as in Hg 1−x Cd x Te grain boundaries (Ludwig et al, 1992). It is important to note that in Ge-bicrystals Uchida et al (1983) found actually the quantum Hall effect (QHE) at T 4.2 K and at magnetic fields above 6 T. The density of carriers at the interface was estimated to be ∼ 5 × 10 12 cm −2 .…”

Evidence for semiconducting behavior with a narrow band gap of Bernal graphite

“…Important to understand the measured behavior of the resistance of graphite samples is the existence of well defined interfaces between the single crystalline regions. As we mentioned in the introduction, interfaces between crystalline regions in semiconductors with different orientations for example [20,21,22,23], lead to confined quasi-two dimensional carrier systems with much larger carrier density than the bulk matrix. We assume therefore that these interfaces running parallel to the graphene layers of the graphite structure are the origin of the metallic like resistivity as well as for the apparent large carrier density measured in bulk samples, i.e.…”

“…As the results from various semiconductors show (e.g. n-Ge bicrystals [20,21], p-InSb [22] as well as in Hg 1−x Cd x Te grain boundaries [23]) internal interfaces lead to the formation of confined quasi-two dimensional carrier systems with n 0 ∼ 10 12 . .…”