Time scale of the excitation of electrons at the breakdown of the quantum Hall effect

Abstract

We have investigated the time scale of the excitation of electrons leading to a transition from the quantum Hall ͑QH͒ state to the dissipative state in the two-dimensional electron systems of GaAs/AlGaAs heterostructures. The measurements were performed by applying nanosecond electric pulses to the current contacts of QH devices having various electron mobilities (1ϫ10 5 р H р9ϫ10 5 cm 2 /V s) at integer filling factors ϭ2, 4, and 6. The breakdown of the quantum Hall effect ͑QHE͒ occurs when the applied pulses exceed a critical pulse width t p c that is a function of pulse amplitude, magnetic field, and electron mobility (0.4рt p c р18 ns). By applying a simple drift model, we obtain an estimate for the critical drift lengths, which vary from about 1 to 25 m. No general differences of the response to short electric pulses have been found between Hall bar and Corbino devices. We interpret the critical times as drifting times between inelastic scattering events, and the critical lengths as related to the inelastic scattering lengths ᐉ in of electrons causing the QHE breakdown. Characteristic dependences of the critical drift times and lengths on the amplitude, filling factor, and the mobility have been observed and can be attributed to impurity-assisted inter-Landau-level tunneling.

Behavior of the contacts of quantum Hall effect devices at high currents

“…According to the present knowledge of this phenomenon, it is established that it has to develop in a sufficiently large domain of high electric field. In that case, the avalanche multiplication of electron hole pairs can occur along the drift of carriers, as well described by the BSEH model [24,26].…”

“…As explained in the bootstrap electron heating model (BSEH) [12,22,23,24,25,26], the electrons propagate their hot temperature. It is then appropriate to measure the longitudinal voltage drops along the electrons paths.…”

Observation of finite excess noise in the voltage-biased quantum Hall regime as a precursor for breakdown

“…[38][39][40] Although these experiments have uncovered important information regarding the QHE breakdown, its mechanism remains to be clarified. 41 Noise measurement is a promising candidate that can provide highly significant information on the QHE breakdown.…”

Optically and electrically induced dissipation in quantum Hall systems

“…Our results show clearly that the current flow in QHSs must contain local contributions [20][21][22][23][24]. Some of our results [22] can also be used to get an explanation for results on the AC QHE. This AC QHE has a good prospective for applications as the comparison of electrical DC units is complicated in practice.…”

“…So far, we can explain certain aspects of these observations by a simple drift model [22,24] and by a twolevel model [25,26]. Our results show clearly that the current flow in QHSs must contain local contributions [20][21][22][23][24].…”