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

We report measurements of the rectification of microwave radiation (0.7–20 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 GHz and different temperatures, the rectified voltage V_dc as a function of microwave power P can be collapsed onto a single universal curve V_dc^*=f^*(P^*) using two scaling parameters. The scaled voltage V_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 n₁ and n₂. Excellent quantitative agreement is obtained between theory and experiment.