Scaling of thermoelectric voltage induced by microwave radiation at the boundary between two-dimensional electron systems

Abstract

We report measurements of the rectification of microwave radiation $(0.7--20\phantom{\rule{0.3em}{0ex}}\mathrm{GHz})$ at the boundary between two-dimensional electron systems created by a narrow gap split gate on a silicon surface for different temperatures, electron densities, and microwave power. For frequencies above $4\phantom{\rule{0.3em}{0ex}}\mathrm{GHz}$ and different temperatures, the rectified voltage ${V}_{\mathit{dc}}$ as a function of microwave power $P$ can be collapsed onto a single universal curve ${V}_{\mathit{dc}}^{*}={f}^{*}({P}^{*})$ using two scaling parameters. The scaled voltage ${V}_{\mathit{dc}}^{*}$ is a linear function of power ${P}^{*}$ for small power and proportional to ${({P}^{*})}^{1∕2}$ at higher power. A theory is developed which attributes the observed voltage to the thermoelectric response associated with local heating by the microwave radiation of adjacent two-dimensional electron systems with different densities ${n}_{1}$ and ${n}_{2}$. Excellent quantitative agreement is obtained between theory and experiment.