RESONANT-CAVITY LIGHT-EMITTING-DIODES FOR THE 3-5-MU-M RANGE

We have realized in the mid-infrared range, resonant cavity light emit ting diodes (RCLEDs). The devices, grown by molecular beam epitaxy of CdHgTe alloys, consist of a bottom Bragg reflector, a half wavelength cavity, n-doped at the beginning (10(18) cm(-3)) and p-doped at the en d (10(18) cm(-3)), containing an active layer at the antinode position , and a top gold mirror which is also used as an ohmic contact. We mea sure a room temperature electroluminescent spectrum full width at half maximum (FWHM) of 9 meV, which is much less than the inhomogeneous li newidth of CdHgTe quantum wells (QWs). Measurements performed at diffe rent temperatures (between 25 and 250 K) show that the temperature cou ld be an efficient means for tuning or detuning the device. Furthermor e, we obtained, at low temperature, an efficient transfer to the cavit y mode due to the good overlap of the Bragg reflector bandwidth with t he CdHgTe emitting spectrum. We have thus demonstrated for the first t ime the feasibility of infrared RCLEDs working up to room temperature. We have also shown that even a relatively low quality factor microcav ity can greatly improve the spectral and spatial characteristics of in frared emitters in the 3-5 mu m range.