THz Magneto-Photoresponse Spectroscopy of Two-Dimensional Electrons in an InAs/InGaAs/InAlAs Inserted-Channel
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We have used THz magneto-photoresponse/transmission to measure various electronic parameters of a two-dimensional electron gas (2DEG) located primarily within an InAs inserted-channel and the surrounding InGaAs well in an asymmetric InAs/InGaAs/InAlAs inserted-well heterostructure in magnetic fields up to 10 T. We have developed an analytical approach to the photoresponse based on resonant heating of the 2DEG by cyclotron resonance (CR) absorption. The analysis incorporates a resonant T-profile mimicking the CR absorption, combined with the theoretical expression for quantized resistance oscillations of a 2DEG. Fitting of an individual set of PR data vs. magnetic field can in principle, provide g-factor, cyclotron effective mass, SdH scattering time, CR scattering time and carrier density of the 2DEs. This is a temperature differential technique, which leads to enhanced sensitivity to harmonic content of the Shubnikov-deHaas (S-dH) oscillations and thus to clearer spin-splitting of the Landau levels at lower fields than is possible in direct S-dH measurements at the same bath temperature. Results show an enhanced g-factor for electrons and large g-factor anisotropy.
KeywordsTHz magneto-photoresponse InAs composite channel 2DEGs Cyclotron resonance absorption
MP and BDM thank J. Wolf for technical assistance in maintaining a supply of liquid helium under difficult circumstances. The work at UB was supported by the National Science Foundation under Materials World Network grant DMR 1008138 and by the Office of the Provost at UB, at the Humboldt-Universität zu Berlin by DFG-MWN grant PAK 556 FI932/4-1, and at the Hamburg University via BMBF, project 01DJ12099 “Era.Net.Rus: SpinBar”.
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