MERCURY CADMIUM TELLURIDE-BASED RESONANT-CAVITY LIGHT-EMITTING DIODE

A CdHgTe resonant cavity light emitting diode (RCLED) is proposed as a new infrared emitter. The device is prepared by molecular beam epitax y on a CdZnTe substrate. A 10.5 periods Bragg mirror is first deposite d. The cavity material is made of Cd0.75Hg0.25Te and contains a wide w ell (50 nm) designed to emit at 3.2 mu m. The last three periods of th e mirror are n-type doped while the cavity material is covered by a th in p-type CdZnTe layer. A gold layer closes the cavity, serving as the second mirror of a Fabry-Perot cavity tuned around 3.18 mu m. It also provides an ohmic contact to the p-region. Under forward bias, the em ission spectrum displays a narrow peak (8 meV full width at half maxim um) corresponding to the cavity resonance. The position and linewidth of this line are independent of temperature. The directivity of the di ode is also improved with respect to a conventional emitter, in agreem ent with theoretical expectations. Taking advantage of the spectral pr operties of the RCLED a new multispectral device has been fabricated.