Thermal Management in Large Bi2212 Mesas used for Terahertz Sources

TL;DR

This paper analyzes the thermal behavior of Bi2212 mesas used for terahertz emission, linking self-heating effects to emission conditions and backbending in the I-V characteristics, with a model predicting temperature and radiation.

Contribution

It introduces a thermal analysis model based on tunneling characteristics to predict temperature and emission behavior in large Bi2212 mesas, explaining backbending phenomena.

Findings

Accessible bias conditions for THz emission despite self-heating

Model accurately predicts mesa temperature and black-body radiation

Backbending linked to Rqp(T) rather than energy gap suppression

Abstract

We present a thermal analysis of a patterned mesa on a Bi2Sr2CaCu2O8 (Bi2212) single crystal that is based on tunneling characteristics of the c-axis stack of ~800 intrinsic Josephson junctions in the mesa. Despite the large mesa volume (e.g., 40x300x1.2 micron3) and power dissipation that result in selfheating and backbending of the current-voltage curve (I-V), there are accessible bias conditions for which significant polarized THz-wave emission can be observed. We estimate the mesa temperature by equating the quasiparticle resistance, Rqp(T), to the ratio V/I over the entire I-V including the backbending region. These temperatures are used to predict the unpolarized black-body radiation reaching our bolometer and there is substantial agreement over the entire I-V. As such, backbending results from the particular Rqp(T) for Bi2212, as first discussed by Fenton, rather than a significant suppression of the energy gap. This model also correctly predicts the observed disappearance of backbending above ~60 K.