Double-peak structure of the nonresonant photoresponse of terahertz quantum Hall detectors

Abstract

We present an approach to the double-peak structure of the nonresonant (bolometric) contribution of the photoresponse, measured as a function of the magnetic field for the optically induced breakdown of the quantum Hall (QH) effect in devices with Corbino geometry. For the optical excitation of our devices, we used a $p$-Ge laser continuously tunable in the wavelength range of $120\text{ }\ensuremath{\mu}\text{m}\ensuremath{\le}\ensuremath{\lambda}\ensuremath{\le}180\text{ }\ensuremath{\mu}\text{m}$. In addition to the bolometric signal, we also observed peaks of the photoresponse due to the cyclotron resonance. In the theoretical part of this study, we present calculations on the basis of an electron heating model. Applying this model we provide a qualitative explanation of our experimental results. To get some insight into the amount of increase in the electron temperature of the QH system exposed to terahertz illumination, we also determined the electron temperature of the QH terahertz detector as a function of the electrical (Joule) heating. Up to about $25\text{ }\ensuremath{\mu}\text{W}$ and at a filling factor of 2, we found a linear increase in the electron temperature with the absorbed power.