Defect Models in Electron-Irradiated N-Type GaAs

1 MeV electron irradiation has been performed in degenerate, n‐type (n≂2×1017 cm-3), molecular beam epitaxial GaAs layers, and Hall effect measurements have been carried out during the irradiation in order to get accurate defect production data. The results have been fitted with statistical models, and are most consistent with the usual E1 (EC-0.045 eV) and E2 (EC-0.15 eV) levels being the (-/0) and (0/+) transitions of the As vacancy, respectively. Also, an acceptor well below EC-0.15 eV is produced at a much higher rate than that of E1 and E2

The pressure method of 1-butene-3-ol epoxidation over Ti-beta catalyst

The investigations of 1-buten-3-ol (1B3O) epoxidation by 30% hydrogen peroxide over Ti-Beta catalyst were performed. The experiments were carried out under the autogenic pressure and at the presence of methanol as a solvent. The influence of the following technological parameters on the course of epoxidation: temperature (20 - 120°C), the molar ratio of 1B3O/H2O2 (0.5:1 - 5:1), methanol concentration (5 - 90 wt%.), Ti-Beta concentration (0.1 - 5.0 wt%) and the reaction time (0.5 - 5.0 h) was investigated. The main functions describing the process were: the selectivity of transformation to 1,2-epoxy-3-butanol in relation to 1B3O consumed, conversions of substrates as well as the selectivity of transformation to organic compounds in relation hydrogen peroxide consumed

\u3cem\u3eIn Situ\u3c/em\u3e Hall-Effect System for Real-Time Electron-Irradiation Studies

A unique system capable of taking in situ Hall‐effect measurements during electron irradiation has been developed. The key element is a small, powerful rare‐earth magnet. Measurements can be taken while the electron beam is on, resulting in a considerable time savings and eliminating problems associated with mounting and demounting the sample. High resolution electron concentration and mobility versus fluence data are quickly and easily obtained, making possible detailed defect production rate studies as functions of energy and flux

\u3cem\u3eIn Situ\u3c/em\u3e Hall-Effect System for Real-Time Electron-Irradiation Studies

A unique system capable of taking in situ Hall‐effect measurements during electron irradiation has been developed. The key element is a small, powerful rare‐earth magnet. Measurements can be taken while the electron beam is on, resulting in a considerable time savings and eliminating problems associated with mounting and demounting the sample. High resolution electron concentration and mobility versus fluence data are quickly and easily obtained, making possible detailed defect production rate studies as functions of energy and flux

Electron-Beam Modification of GaAs Surface-Potential - Measurement of Richardson Constant

The surface potential of GaAs is strongly modified in the presence of a high‐energy electron beam due to the creation of electron‐hole pairs in the depletion region and the subsequent drift of the holes to the surface where they neutralize surface states. This effect is modeled in terms of a parameter K=A∗T2/Ib(dE/dz)η, where Ib is the beam current density, A∗ is the effective Richardson constant, dE/dz is the beam energy loss per unit length, and η−1 is the average energy required to create an electron‐hole pair. For the sample studied here, an 0.25‐μm layer with n≂3×1017 cm−3, we obtain a value K≂(7.5±0.8)×104 cm at T=296 K and Ib=0.33 μA/cm2, which gives A∗≂0.44 A/cm2 K2. Although this value of A∗ is much lower than the theoretical estimate of 8 A/cm2 K2, it is in good agreement with other recent results

\u3cem\u3eIn Situ\u3c/em\u3e Hall-Effect System for Real-Time Electron-Irradiation Studies

A unique system capable of taking in situ Hall‐effect measurements during electron irradiation has been developed. The key element is a small, powerful rare‐earth magnet. Measurements can be taken while the electron beam is on, resulting in a considerable time savings and eliminating problems associated with mounting and demounting the sample. High resolution electron concentration and mobility versus fluence data are quickly and easily obtained, making possible detailed defect production rate studies as functions of energy and flux