II-VI resonant cavity light emitting diodes for the mid-infrared

A CdHgTe low-Q resonant cavity light emitting diode is proposed as a new infrared light source. The device consists of a bottom Bragg reflector, a half-wavelength cavity containing an active layer at the antinode position, n-doped with indium on one end and p-doped with nitrogen on the other, and a 0.95 reflectance top gold mirror which also serves as an ohmic contact. The emission spectra at room temperature show a narrow peak, the full width at half maximum (FWHM) of which is much less than the natural emission peak FWHM of CdHgTe quantum wells. The emission directivity is shown to be improved by the cavity effect. The room temperature external quantum efficiency (EQE) reaches 2 . 10(-4) at 3.2 mu m and 2.5 . 10(-4) at 4.1 mu m. Infrared emitters in the 3-5 mu m wavelength range can therefore benefit from the enhanced spectral, spatial and temperature characteristics of resonant microcavities.