Papers by Keyword: GaSb

Abstract: The III-V compound semiconductors exhibit the advantage of wide bandgap and high electron mobility, making them appropriate for optoelectronics and microelectronics sector. Vertical directional solidification (VDS) is a technique developed to grow the high quality III-V semiconducting bulk crystals. One of the Sb based III-V materials, Gallium Antimonide (GaSb) was grown by VDS. This direct band gap semiconductor was realized as a ρ-type substrate and thermally diffused in vacuum by Tellurium (Te) ions as n-type dopant to fabricate ρ-n junction. Fabrication of successful ρ-n junction was confirmed by its electrical behaviour. It was later subjected to furnace annealing in vacuum at 200°C and 400°C for dopant to compensate deep in crystal geometry. Rectification characteristics of this junction were distinctly sharp for either biasing. It is revealed that rectification was approaching to optimum ideality factor (1-2) after vacuum furnace annealing at higher temperature. This device exhibits an applicability for NIR sensing close to 1.7µm.

Abstract: Successively forming GaSb islands by solid-phase epitaxy and covering them with a silicon layer, a nanostructured material containing 4 layers of GaSb nanocrystals (NCs) was grown on Si (111) surface. Due to a small size of the NCs (average height ~ 1.7 nm, average lateral size ~ 14 nm) and, as a consequence, to a significant quantum-size effect, a high electrical conductivity (~ 100 Ω^-1·cm^-1 at 600 K) together with a low thermal conductivity (~ 1 – 1.5 W·m^-1·K^-1 at 600 K) was obtained in the nanostructured material Si/NC_GaSb/Si. As a result, the thermoelectric figure of merit of the material has reached 0.82 at 600 K.

Abstract: We study the GaSb/GaAs nanostructures (NSs) grown by droplet epitaxy technique with various Ga amounts. Ga amount deposited on the GaAs (001) substrate was varied between 3-5 ML to form the different size and density of liquid Ga droplets. The Sb flux was subsequently irradiated to crystallize the droplets. Morphology of GaSb NSs was investigated by atomic force microscopy (AFM). Quantum rings were obtained after crystallizing 3-ML Ga droplets, whereas some kind of quantum dots were formed after crystallizing 4-and 5-ML Ga droplets. The formation mechanisms leading to the different structure are discussed. The photoluminescence (PL) measurement was performed to examine the optical properties of GaSb/GaAs NSs.

Abstract: A brief historical overview of one of Hungary's space projects on Soviet spacecrafts, the so-called "Eötvös" Project on semiconductor crystal growth, is given. Three experiments were proposed and performed: i) epitaxial growth of GaAs under flux, ii) seedless growth of GaSb, and as a control, iii) seeded growth of an InSb crystal. Because of thermal control problems of the furnace, only the growth of a structurally perfect GaSb bicrystal was a successful novelty. Results of structural and electrical analyses are briefly summarized. Finally, a list of related publications is given.

Abstract: Defects induced by electron irradiation in Te-doped liquid-encapsulated Czochralski–grown GaSb were studied by the positron lifetime spectroscopy. The lifetime measurements under room temperature indicated there were VGa-related defects with a characteristic lifetime of 298 ps in the heavily Te-doped as-grown GaSb samples. The average lifetime increased with the increase of irradiation dose in lightly Te-doped GaSb,but the behavior was opposite in the heavily Te-doped samples. It should be due to the shift of Fermi level in heavily Te-doped GaSb and the occurrence of gallium vacancies in different charge states. In the temperature dependence measurements carried out on heavily Te-doped samples, we observed positron shallow trap, and this shallow trap should be attributed to positrons forming hyrogenlike Rydberg states with GaSb antisite defects.

Abstract: Fabrication of surface-relief microstructures in GaSb for application in mid-infrared optoelectronic devices is described. Photo- and e-beam lithography was used to define patterns on GaSb surfaces. Ar/O2 sputter etching and RIE in BCl3-based plasma were applied to transfer preshaped master into the GaSb substrate. Circular microlenses with an aspect ratio (height to diameter) 0.4/10 µm and circular gratings with 0.4 µm linewidth / 1 µm period and 1.7 µm depth have been demonstrated.