Resistance fluctuation and amplitude response for THz irradiation. Most cycles follow a bolometric response, while a few cases follow a nonlinear response. The nonlinear response arises from the excitation of extra carriers which is reflected as an opposite response in the resistance change compared to the bolometric response.
Mahjoub et al. Nanoscale Research Letters 2013 8:22 doi:10.1186/1556-276X-8-22