Temperature dependence of far-infrared electroluminescence in parabolic quantum wells

We have measured the far-infrared emission from parabolically graded quantum wells driven by an in-plane electric field in the temperature range from 20 to 240 K. The peak emission corresponds to the intersubband plasmon in the parabolic potential. Its photon energy (6.6/9.8 meV) remains rather unaffected by temperature variations, the full-width at half-maximum ranges from 1 (T=20 K) to 2 meV (T=240 K). The reduction of emission efficiency with increasing temperature is attributed to the change in the nonradiative lifetime. (C) 1999 American Institute of Physics. [S0003-6951(99)05021-4].