[en] This thesis describes experiments on the behaviour of deep level defects in the semiconductors Ge, Si and GaAs. The gamma irradiation of p-type Ge crystals grown from silica crucibles under a hydrogen atmosphere always produces two deep acceptor levels. Evidence is presented to show that these are most likely due to oxygen-vacancy complexes. Heat treating samples before irradiation appears to reduce the amount of oxygen available for production of the deep levels, and so these samples are hardened to radiation damage. Similarly, Li ions drifted through the crystal cause radiation hardening of this material, possibly by binding oxygen into stable Li-O pairs, and also by direct passivation of the gamma-induced defect centres. Proton and neutron irradiation of Ge produced acceptor levels only, whereas gamma-damage produced both donor and acceptor levels. Deep level defects in single crystal and polycrystalline GaAs are discussed. The fabrication of thin, highly doped contacts to semiconductors by pulsed laser melting of an evaporated dopant layer is considered. The use of Li to produce n⁺ layers has met with the most success, and good quality Si and Ge radiation detectors were fabricated in this fashion. Energy levels and capture cross sections of defects related to over 25 different elemental impurities introduced into Ge were measured. Finally, experiments in which point defects in Ge and GaAs are neutralised by the incorporation of atomic hydrogen are discussed

[en] All p-type Ge grown by the Czochralski technique from silica crucibles under an H₂ atmosphere shows two dominant acceptor defects on γ irradiation. Measurements by DLTS are reported which support the hypothesis that these centres (Esub(v) + 0.23 eV, Esub(v) + 0.38 eV) are most likely due to complexes between oxygen and lattice vacancies

[en] This book collects papers on semiconductor materials. Topics include: oxygen precipitation formation, silicon, boron complexes in silicon, radiation-induced defects in indium antinomide, gallium arsenides, vapor phase epitaxy, gallium and indium phosphides, crystal doping, and deep level transient spectroscopies

[en] Deep level transient capacitance spectroscopy has been used to examine γ-ray induced defect centres in germanium crystals grown under widely varying conditions. A deep acceptor level at Esub(v) + 0.38 eV has been observed for the first time in all p-type samples; this was removed by annealing at 675 deg C for three hours. A new, deep donor level at Esub(c) - 0.42 eV observed in n-type material was not removed by this procedure

[en] A deep level transient capacitance spectroscopy (DLTS) system, modified for the measurement of transient conductance, has been used to observe gamma-ray induced defect centres in the gate junction of 2N4416 Si field effect transistors. The defect concentrations increased linearly wth gamma-dose in the range 50 kGy to 10 x 10³ kGy (5-1000 Mrad) for the common Esub(c) - 0.17 eV level, and in the range 500 kGy to 10 x 10³ kGy (50-1000 Mrad) for the levels Esub(c) - 0.22 eV and Esub(c) - 0.44 eV. Another common level, a hole trap at Esub(v) + 0.42 eV, was the only minority trap observed. The technique may be useful for measur-ing gamma-fluxes in situations inaccessible to standard dosemeters (e.g. flux-mapping)

[en] Deep level transient spectroscopy (DLTS) has been applied to defect centres in γ-ray compensated germanium that has been subjected to long-term annealing at room temperature. Deep donor levels (Esub(c) - 0.36 eV, Esub(c) - 0.20 eV) have been observed for the first time; annealing at 675 deg C for 3 hours increased their concentration in proportion to the free carrier density, indicating stable defect-impurity complexes. Recently irradiated samples from the original material have not shown these levels. The results support Russian work on the compensation mechanism - the formation of electically inactive vacancy-donor complexes

[en] Deep level transient spectroscopy has been applied for the first time to the study of deep level defects in n-GaAs nuclear radiation detectors. Devices made from commercial bulk and epitaxial material with net donor impurity densities in the range 5 x 10¹³ - 3 x 10¹⁶ cm^-3 have been studied and several common levels observed. The Poole-Frenkel effect has been identified in three levels (Esub (v) + 0.19 eV, Esub(c) - 0.62 eV, Esub(c) - 0.73 eV) in the epitaxial GaAs. A value for the Poole-Frenkel constant of β 4.7 +- 1.4 x 10^-4 eV Vsup(-1/2) cmsup(1/2) was obtained, compared to the theoretical value for GaAs of 2.3 x 10^-4 eV Vsup(-1/2) cmsup(1/2)

[en] Results of work on the behaviour of deep level impurities in the semiconductors Ge, Si and GaAs, within the context of solid-state nuclear radiation detectors, are reported. The main measurement technique used was deep level transient spectroscopy. Effects of lithium and hydrogen on gamma radiation damage have been investigated

[en] Maximum hole densities of 4 x 10¹⁸ cm^-3 were produced in Al_0.3Ga_0.7As by C + Ga implantation and subsequent annealing at ∼ 800 C. The activation efficiency decreases with increasing AlAs mole fraction and the use of higher temperatures for the Ga co-implantation due to a reduced vacancy concentration under these conditions. The C diffusivity is ≥ 2 x 10^-13 cm²sec^-1 at 950 C in implanted Al_0.3Ga_0.7As, demonstrating that C is a much more thermally stable acceptor than Be, Mg, or Zn

[en] A new group of deep donors, designated E /SUB T/ I, has been studied in as-grown n-type ultrapure germanium single crystals ((N /SUB D/ - N /SUB A/ ) about 10¹⁰ cm^-3). The donors have a broad band-type structure consisting of three or more closely spaced peaks (E /SUB c/ -40 meV to E /SUB c/ -100meV) as determined by deep level transient spectroscopy (DLTS). Reverse electrode germanium (REGe) radiation detectors which contain E /SUB T/ I are shown to exhibit electron trapping leading to a degradation in resolution as measured by the 1.33 MeV γ-ray peak of ⁶⁰Co. The concentration of E /SUB T/ I and the degradation in resolution are strongly correlated