High-resolution electron microscopy is used to investigate the morphology of ultrathin pseudomorphic (001) ZnTe and MnTe strained layers grown in CdTe. Local distortions of the crystal lattice are measured directly on high-resolution images by use of image processing software. In the case of ZnTe/CdTe superlattices, the method yields the location of Zn within each place in the heterostructure and the total amount of Zn per period. For MnTe layers embedded in CdTe, one can deduce the atomic morphology of the interfaces which are shown to present a clear asymmetry.

CdTe and Cd1−xZnxTe layers and microstructures were doped with indium donors during their growth at low temperatures (200–220 °C) by molecular-beam epitaxy under Cd overpressure. Uniform and planar doping of layers and local doping of quantum wells and superlattices are presented. Characterization techniques include secondary-ion mass spectroscopy (SIMS), capacitance-voltage and Hall-effect measurements, optical spectroscopy, x-ray double diffraction, and x-ray photoelectron spectroscopy. In the range of indium concentrations 2×1016–1×1018 cm−3, the donor activation efficiency is 100% for uniform doping. A low-temperature carrier mobility of up to 5300 cm2/V s is obtained. The highest measured carrier concentration is 1.3×1018 cm−3; at a higher doping level, strong compensation occurs, related to dopant migration and cadmium vacancy formation. Planar doping also yields ≊100% activation efficiency for moderate values of sheet density (≊1011 cm−2) but has the same limit of about 1018 cm−3 for total carrier concentration. High-structural-quality planar-doped quantum wells and superlattices are obtained. Good localization of dopant is demonstrated by SIMS at low sheet density but at high concentration substantial migration of indium occurs.

Experiments have been designed to measure the interdiffusion coefficients in CdTe/HgTe (001) superlattices grown by molecular beam epitaxy. The interdiffusion coefficients are deduced from double-crystal x-ray diffraction on samples annealed in the 200–240 °C range under a Hg saturated pressure. Our results indicate that the interdiffusion is strongly dependent on concentration with a coefficient given by D(CCd,T)=1.0 exp{[−1.45(±0.1) eV]/(kT)} exp {[−0.55 (±0.1) CCd eV]/(kT)} cm2/s. The activation energies ΔEHgTe≊1.45 eV and ΔECdTe≊2.0 eV are consistent with an interdiffusion process by a vacancy mechanism.