Giant microwave photoresistance of two-dimensional electron gas

Abstract

We measure microwave frequency (4-40 GHz) photoresistance at low magnetic field B, in high mobility 2D electron gas samples, excited by signals applied to a transmission line fabricated on the sample surface. Oscillatory photoresistance vs B is observed. For excitation at the cyclotron resonance frequency, we find an unprecedented, giant relative photoresistance (\Delta R)/R of up to 250 percent. The photoresistance is apparently proportional to the square root of applied power, and disappears as the temperature is increased.Comment: 4 pages, 3 figure

Zero-Differential Resistance State of Two-Dimensional Electron Systems in Strong Magnetic Fields

“…[3,4,5,6] This so-called zero resistance state (ZRS) has stimulated extensive theoretical interest. [7,8,9,10,11,12] At higher magnetic field ω c > ω a considerable decrease of magnetoresistance with microwave power is found [2,5,6] which has been attributed to intra-Landau-level transitions. [13] Another interesting nonlinear phenomena have been observed in response to DC electric field.…”

Calculation of the nonlinear free-carrier absorption of terahertz radiation in semiconductor heterostructures

“…Such a current cannot be obtained from the previous theory [12][13][14][15][16] because the current obtained there vanishes when the probing field is removed. Furthermore, in the limit of zero radiation field, all existing theories predicted a quadratic dependence of the current on the radiation field while the experiment 11 clearly shows a linear dependence.…”

“…It is consistent with the linear dependence found in the experiment. 11 Since the magnetic field is absent in the current calculation, we cannot make a direct comparison with the experiment. However, we do not expect that application of a constant magnetic field will alter such a linear dependence.…”

“…THz lasers have been applied to experimental investigation of nonlinear transport and optical properties in electron gases such as those in semiconductor quantum wells and heterostructures. [1][2][3][4][5][6][7][8] The discovery of a new magnetoresistance oscillation and zero-resistance state in high-mobility electronic systems [9][10][11] has stimulated new theoretical interest in the transport properties of electrons under electromagnetic radiation. [12][13][14][15] A satisfactory understanding of the observed dc magnetoresistance oscillation has been achieved.…”

Microwave-induced zero-resistance states are not necessarily static

“…A related phenomenon of microwave-induced resistance oscillations had been observed earlier in samples of lower quality, in which there are changes in the dc resistance produced by the microwave irradiation, which depend in an oscillatory manner on the ratio of the microwave frequency to the cyclotron frequency of the 2DEG, but where the resistance was not driven down to zero. 5,6 Following the discovery of the ZRS, a phenomenological explanation was put forward. 7 It was assumed that for microwave power above a certain threshold, for an appropriate sample, in certain ranges of the magnetic field and microwave frequency, the microwave-induced resistance oscillations would increase to the point where the differential longitudinal conductivity would become negative at zero dc electric field, and it was noted that in this case that the zeroelectric-field solution would necessarily be unstable.…”