The deep levels present in semiconducting CdTe and semi-insulating CdTe:Cl and Cd0.8Zn0.2Te have been investigated by means of cathodoluminescence, deep level transient spectroscopy (DLTS), photo-induced current transient spectroscopy, and photo-DLTS. The latter two methods, which can be applied to semi-insulating materials, allow to characterize the deep traps located up to midgap and can determine whether they are hole or electron traps. We have identified 12 different traps, some common to all the investigated samples, some peculiar to one of them. A comparison of the results obtained from the various materials is given and the status of defect models is reviewed.

Ga 2 O 3 nano-and microwires with diameters ranging from tens of nanometers to about one micron and lengths of up to tens of microns, have been obtained by sintering Ga 2 O 3 powder under argon flow. The structures have been investigated by cathodoluminescence in the scanning electron microscope. The samples showed the violet-blue emission characteristic of Ga 2 O 3 and a red emission at 1.73 eV dominant in the nanowires and other nano-and microstructures formed during the sintering treatment. At temperatures below 210 K, this band exhibits sharp peaks separated by 20 meV. This observation suggests the exchange of phonons in the recombination process.

Red luminescence emission from chromium doped ␤-Ga 2 O 3 nanowires has been studied by means of photoluminescence ͑PL͒ techniques. PL excitation shows several bands in the ultraviolet-visible region. Time decay values, obtained by time resolved PL, at different temperatures fit a three level model with thermal population of the upper level from the middle one. From the results, the origin of the emission is assigned to Cr 3+ ions in the ␤-Ga 2 O 3 host, and values for the energy level separation and Huang-Rhys factor of the broad 4 T 2 -4 A 2 emission are estimated.

Sintering SnO 2 under argon flow at temperatures in the range of 1350-1500°C causes the formation of wires, rods, and tubes on the sample surface. At high temperatures of the mentioned range, microwires with lengths of hundreds of microns are formed. At lower temperatures the formation of micro-and nanorods as well as micro-and nanotubes takes place. The influence of ball milling of the starting powder on the formation of tubes is investigated. The local cathodoluminescence measurements show a different defect structure in the tubes than in the sample background.

Indium oxide elongated micro- and nanostructures have been grown by thermal treatment of InN powder. Chains of nanopyramids connected by nanowires, forming a necklace-like structure, as well as cubes and arrow-like structures consisting of a long rod with a micron size pyramid on the top, grow at temperatures in the range 600–700°C in a catalyst free process. The structures have been characterized by scanning electron microscopy and cathodoluminescence.