A. Venter

Characterization of the E(0.31) defect introduced in bulk n-Ge by H or He plasma exposure

Bulk antimony (Sb) doped germanium (n-Ge) samples with doping concentrations ranging between 7.0 × 1014 cm−3 and 2.5 × 1015 cm−3 were exposed to a dc-hydrogen or helium plasma. Hydrogen exposure resulted in the introduction of a single prominent defect level at EC −0.31 eV. Exposing similar samples to He plasmas introduced the same electron trap. The trap concentration increased linearly with dopant concentration suggesting that Sb may be a component of this plasma-induced trap. Thermal annealing kinetics studies suggested that this defect anneals out by diffusion.

Ar plasma induced deep levels in epitaxial n-GaAs

Ar plasma etching of n-type (Si doped) GaAs introduces several electron traps (Ec - 0.04 eV, Ec - 0.07 eV, Ec - 0.19 eV, Ec - 0.31 eV, Ec - 0.53 eV, and Ec - 0.61 eV). The trap, Ec - 0.04 eV, labelled E1′ and having a trap signature similar to irradiation induced defect E1, appears to be metastable. Ec - 0.31 eV and Ec - 0.61 eV are metastable too and they are similar to the M3/M4 defect configuration present in hydrogen plasma exposed n-GaAs.

Laplace deep level transient spectroscopy of electron traps in epitaxial metalorganic chemical vapor deposition grown n-GaSb

Three prominent electron traps, 0.167 eV, 0.243 eV, and 0.295 eV below the conduction band minimum were detected in Te doped MOCVD grown n-GaSb using an Au Schottky barrier diode. The free carrier concentration of the ∼3 μm epilayer grown on n+ (>1018 cm−3) substrate, confirmed by Hall and capacitance-voltage measurements, was 5–7 × 1016 cm−3. The low doping concentration of the epitaxial layers was achieved using diethyl tellurium as the dopant source. Defect concentration profiles suggest that Ec-0.167 eV and Ec-0.243 are predominantly confined to the surface of the epilayer and that the concentration, thereof, approximates the free carrier concentration of the material close to the metal-semiconductor interface.

Comprehensive study of ZnO nanostructures grown using chemical bath deposition: from growth to application

ZnO nanostructures were grown using a simple and environmentally friendly chemical bath deposition technique on pre-treated p-type silicon substrate at temperatures below 100°C. The effects of growth parameters like seed layer density, growth time, growth temperature, precursor concentration and annealing temperature on the structural, morphological, electrical and optical properties of ZnO nanorods were systematically studied using field emission scanning electron microscopy, X-ray diffraction, photoluminescence spectroscopy and current-voltage measurements. A variety of architectures is demonstrated, ranging from single crystalline nanoparticles and c-axis orientated nanorods to highly compact crystalline thin films. Post-growth annealing at different temperatures profoundly affects the optical properties of the nanorods by, for example, reducing hydrogen- and intrinsic defect-related emission. The rectifying properties of the ZnO/Si heterojunction are discussed.

Photoluminescence of chemically treated InAs (111)A

Variable laser power and temperature dependent photoluminescence (PL) measurements were used to identify some of the optical transitions and impurity-related emissions for chemically treated (Br-methanol, (NH4)2S + S or [(NH4)2S/ (NH4)2SO4] + S solutions) or oxidised (annealed in oxygen) bulk n-InAs (111)A. A combination of PL and X-ray photoelectron spectroscopy (XPS) measurements before and after various treatments was used to identify the chemical nature of the impurities giving rise to bound exciton recombination in InAs (111). Band–to-band transitions have been observed at 0.4185 eV. In addition, two shallow neutral donor bound excitons ascribed to atomic oxygen (at 0.412 eV) and to sulphur (at 0.414 eV), have been detected after treatment.

Field dependence of the E1′ and M3′ electron traps in inductively coupled Ar plasma treated n-Gallium Arsenide

Inductively coupled Ar plasma etching of n-type (Si doped) Gallium Arsenide (GaAs) introduces several electron traps, Ec – 0.04 eV (labelled E1 0 ), Ec – 0.19 eV, Ec – 0.31 eV, Ec – 0.53 eV, and Ec – 0.61 eV (behaving like the well documented M3 and labelled M3 0 in this study), of which the metastable defects Ec –0 .04 eV (E1 0 ), and Ec – 0.07 eV are novel. Furthermore, E1 0 and M3 0 exhibit strong field enhanced carrier emission. Double-correlation deep level transient spectroscopy was used to investigate the field dependent emission behaviour of these two defects. It is shown that for both traps, the observed enhanced emission is due to phonon assisted tunnelling. The latter observation is contrary to the literature reports suggesting that enhanced carrier emission for M3 occurs via the Poole-Frenkel mechanism. V C 2012 American Institute of Physics.