II-VI Semiconductor microstructures : from physics to optoelectronics

(Received 22 February 1994, accepted 2 May 1994)

Abstract
The tellurium compounds family displays many interesting features. The various compounds cover a very large range of bandgap energies from 0 (Cd _0.15H Te) to more than 3 eV (ZnTe : 2.4 eV ; MnTe : 3.2 eV ; MgTe : 3.5 eV). The lattice parameters of the various compounds are sometimes almost perfectly matched, as in the CdTe/Cd _xHg _1-xTe case, or slightly enough mismatched for a coherent epitaxy to be performed. Furthermore, good quality Cd _0.96Zn _0.04Te substrates are now available which allow to grow a large variety of microstructures using molecular beam epitaxy. The thickness control of the deposited layers allows to design and grow sophisticated beterostructures incorporating monolayer thick features. The direct band gap of these materials makes them well-suited to many optoelectronic applications in the infrared and visible range. A few examples of applications are described in more details : i) microtip semiconductor laser based on a cold microtip electron emitter for cathodic pumping of a CdTe/CdMnTe laser cavity ; ii) multiquantum well structures showing a marked excitonic absorption band at room temperature and the disappearance of this band when an electric field is applied to the structure. Application to self electrooptic and photorefractive devices ; iii) Bragg mirrors for the infrared. In addition to the usual semiconductor properties, the manganese compounds display interesting properties which can be useful in the field of magnetooptics.