Recently, geometry-induced quantum effects were observed in periodic nanostructures. Nanograting (NG) geometry significantly affects the electronic, magnetic, and optical properties of semiconductor layers. Silicon NG layers exhibit geometry-induced doping. In this study, G-doped junctions were fabricated and characterized and the Fermi-level tuning of the G-doped layers by changing the NG depth was investigated. Samples with various indent depths were fabricated using laser interference lithography and a consecutive series of reactive ion etching. Four adjacent areas with NG depths of 10, 20, 30, and 40 nm were prepared on the same chip. A Kelvin probe was used to map the work function and determine the Fermi level of the samples. The G-doping-induced Fermi-level increase was recorded for eight sample sets cut separately from p-, n-, p+-, and n+-type silicon substrates. The maximum increase in the Fermi level was observed at a10 nm depth, and this decreased with increasing indent depth in the p- and n-type substrates. Particularly, this reduction was more pronounced in the p-type substrates. However, the Fermi-level increase in the n+- and p+-type substrates was negligible. The obtained results are explained using the G-doping theory and G-doped layer formation mechanism introduced in previous works.
In the present work, we report the result of the study of electron and γ-radiation effect on the parameters of normally open and normally closed field effect transistors with Shottky barrier on GaAs. It has been shown that normally closed transistors are more sensitive to the action of radiation than normally opened transistors. Both transistors are more sensitive to the electron radiation. As substrates ware used epitaxial structures of GaAs of n-type conductivity doped with tellurium with ND
=2×1017 cm3 with surface orientation [100]. Electron irradiation was conducted on the linear accelerator of RELUS type with electron energy 4 MeV at the room temperature, with the intensity of electrons flow of 2.5×1012 e/cm2 sec. Integral doses made 1×1014 e/cm2, 5×1014 e/cm2, 1×1015 e/cm2 and 3×1015 e/cm2. The γ-radiation was conducted using the source 60Co at the room temperature with the intensity of 5×103 P/sec. For the γ-radiation, visible changes of saturation flow current are observed at the doses of more than 105 Grey (GaAs). As whole, the γ-radiation makes an action on the parameters of MESFET in the less degree than electron irradiation. The annealing of the irradiated samples of MESFET at the temperature of 573 K in the nitrogen atmosphere for 45 min provides complete restoration of their parameters. The possible reasons for the mentioned effects are given.
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