W. Dobrowolski

Effect of Mn interstitials on the lattice parameter of Ga1−xMnxAs

Structural investigation of as-grown as well as annealed Ga1−xMnxAs epilayers was carried out using high-resolution x-ray diffraction (XRD) measurements for a wide range of Mn concentrations (0.027⩽x⩽0.083), with special attention on how the interstitial Mn atoms (MnI) influence the lattice parameter of this material. We observe a distinct decrease of the lattice parameter after low-temperature annealing of Ga1−xMnxAs, which is known to reduce the MnI concentration. The reciprocal space maps measured for all of the investigated samples showed that the Ga1−xMnxAs layers are fully strained—i.e., they remain pseudomorphic to the GaAs (001) substrate—for the entire thickness of the samples used (in the present case over 100 nm). In all cases studied, the XRD measurements revealed high crystalline perfection of both as-grown as well as annealed Ga1−xMnxAs epilayers.

Properties of epitaxially grown CdTe layers doped with indium

Abstract We report on the growth and characterization of n-type indium-doped CdTe films grown by molecular beam epitaxy on GaAs substrates. By varying the In flux we are able to control the carrier concentration in the range from 8 × 1014 to 1.5 × 1018 cm−3. The samples have been investigated by photoluminescence, transport, and deep level transient spectroscopy (DLTS) measurements. By DLTS we established that the concentration of the dominant electron trap, located at 0.45 eV below the edge of the conduction band, is proportional to the net donor concentration. This result indicates that the trap may be related to the presence of indium dopants.

Magnetoresistance near the ferromagnetic-paramagnetic phase transition in magnetic semiconductors

Magnetic and transport properties of ferromagnetic semiconductors (FMSs) near the ferromagnetic-paramagnetic phase transition were studied in two classes of FMSs: in the III–V-based In1−xMnxSb and Ga1−xMnxAs epitaxial films and in IV–VI-based Sn1−xMnxTe and Sn1−x−yMnxEryTe alloys in bulk crystal form. Magnetoresistance data for both FMS classes are in excellent agreement with the theory of Majumdar and Littlewood, indicating that near the Curie temperature, magnetic fluctuations play a key role as scattering centers. These results also show that the Majumdar–Littlewood model can be applied to magnetically very dilute systems.

Effect of annealing on magnetic and magnetotransport properties of Ga1−xMnxAs epilayers

Abstract High-field magnetic measurements performed with the use of magnetooptical Kerr effect in the polar configuration as well as high-field and low-field magnetotransport studies were carried out on Ga 1− x Mn x As epilayers grown by low-temperature molecular beam epitaxy, and subsequently annealed under various conditions. The structural investigations by means of high resolution XRD were also performed. We observe significant changes in magnetoresistivity curves, magnetization and strain introduced by the annealing.