Silicon oxide based and aluminum gated MOS structures fabricated on n-type silicon are investigated after irradiation with low energy electrons in scanning electron microscope. The thermally stimulated current (TSC) technique in the temperature range from 80 K to 320 K revealed a number of the electron beam induced charge traps. With the help of the capacitance-voltage method, the traps revealed by the TSC were identified by their location (within dielectric, semiconductor or at the interface) and by their nature (trap for electrons or for holes).

We demonstrate significant improvement of the radiation immunity of the integrated circuits based on silicon bipolar transistors. Strong decrease of the current gain degradation and significant yield improvement after high-energy gamma irradiation are both shown. This was achieved by development of efficient hydrogenation process for the silicon bulk and the surface dielectric layer using electron cyclotron resonance (ECR) plasma, as well as implementation of effective Si-wafer gettering option. Keywords: integrated circuits, bipolar transistors, ECR-plasma, hydrogenation of semiconductor structures, trap state passivation, gettering of semiconductor wafers, γ-irradiation, radiation hardness, yield of workable transistors.

This paper presents the results of hydrogen electron-cyclotron resonance (ECR) plasma in microelectronics technology. Its effect on the radiation resistance of the IC and on the quality of the ohmic contact during the formation of UBM metallization is demonstrated. The devices obtained with the use of plasma ECR and without it are analyzed.

We demonstrate significant improvement of the radiation immunity of the integrated circuits based on silicon bipolar transistors. Strong decrease of the current gain degradation and significant yield improvement after high-energy gamma irradiation are both shown. This was achieved by development of efficient hydrogenation process for the silicon bulk and the surface dielectric layer using electron cyclotron resonance (ECR) plasma, as well as implementation of effective Si-plate gettering option.

The extraordinary behavior of the oxide charge in SiO 2 /Si structures processed under the conditions reproducing chemical-vapor-deposition (CVD) growth of thin carbon films is reported. The charge in the SiO 2 dielectric layers and the SiO 2 /Si interface quality in the structures subjected to high-temperature annealing in a CVD reactor were studied using a high-frequency capacitance–voltage technique. It is shown that a huge positive charge is generated in the SiO 2 dielectric layers under annealing in an ethanol-containing atmosphere at temperatures of about 600–700°C. The surface density of the induced oxide charge can be as high as 4 × 10 12 cm −2 and is expected to strongly influence the parameters and performance of fabricated metal–oxide–semiconductor devices. The positive charge induced in the SiO 2 layers is presumably related to carbon diffusion which starts to be effective at 600–700°C. The quality of the SiO 2 /Si interface significantly degraded after annealing at temperatures higher than 700°C, however, no explicit relationship to a precursor used for CVD growth was found.

Among the different graphene derivatives, graphene oxide is the most intensively studied material as it exhibits reliable and repeatable resistive switching. The operative mechanisms that are responsible for resistive switching are being intensively investigated, and three models explaining the change in the resistive states have been developed. These models are grounded in the metallic-like filamentary conduction, contact resistance modification and the oxidation of/reduction in the graphene oxide bulk. In this work, using Al/GO/n-Si structures, we demonstrate that all three of these operative mechanisms can simultaneously participate in the resistive switching of graphene oxide. Multiple point-like conduction channels in the graphene oxide films were detected by the electron beam-induced current (EBIC) technique. At the same time, large areas with increased conductivity were also revealed by EBIC. An analysis of these areas by Raman spectroscopy indicates the change in the graphene oxide bulk’s resistive properties. The EBIC data along with the measurements of the capacitance–voltage characteristics provided strong evidence of the involvement of an aluminum/graphene oxide interface in the switching processes. In addition, by using Al/GO/n-Si structures, we were able to identify unique local properties of the formed conductive channels, namely the change of the charge state of a conductive channel due to the creation of negatively charged traps and/or an increase in the GO work function.

Graphene‐like films (GLFs) are selectively deposited on the silicon oxide/silicon structures preirradiated with electrons at various electron energies and irradiation doses. These films demonstrate high conductivity and are used as a gate material for metal‐oxide‐semiconductor (MOS)‐based devices. It is shown that high‐quality capacitance–voltage characteristics of the GLF‐gated MOS structures can be obtained if both an energy and a dose are carefully tuned. Using the GLF‐gated MOS as a pseudo‐field effect transistor structure, a notable current modulation in the selectively grown GLF is observed.

The paper discusses methods for increasing the resistance of silicon semiconductor devices to ionizing radiation. A key feature of the presented methods is that there is no need to modify the topology, i.e. the described technological methods make it possible to increase the stability of integrated circuits by adding some technological operations to the standard process flow (not radiation hardy).

Silicon oxide based, aluminum gated MOS structures fabricated on n-type silicon were subjected to a low energy electron beam irradiation in the scanning electron microscope. The induced interface states and the oxide charges were studied by the high frequency capacitance-voltage technique as a function of the electron beam energy, irradiation dose, annealing time, temperature and electric field. Strong initial increase and subsequent saturation of the donor-like interface state density with the irradiation dose was observed for all electron beam energies used. Besides, shallow positively charged traps were found to be formed in the silicon oxide after irradiation, while at the initial stage of irradiation the formation of a negative charge was established. The irradiation induced interface states and the positively charged shallow oxide traps demonstrated notable reduction at room temperature. Zero bias annealing at the temperatures of about 250-300 degrees C resulted in a complete removal of the interface states and partial compensation or elimination of the oxidation induced positive fixed charge, presumably due to remaining negative charge in oxide.

The diode p-(Ga,Mn)As/n-InGaAs/n+-GaAs heterostructures, which differ in thickness (from 5 to 50 nm) of a diluted magnetic semiconductor (Ga,Mn)As layer, were fabricated and studied. We found the negative magnetoresistance effect, reaching 6–8% in a 3600 Oe magnetic field. The effect was conserved up to temperatures of 70–80 K and associated with a decrease in charge carrier scattering due to ferromagnetic ordering in the (Ga,Mn)As layer. The dependence of the magnetoresistance on the forward bias voltage is nonmonotonic with the maximum magnetoresistance and its observation voltage range depending on the (Ga,Mn)As layer thickness. The magnetic field dependences of the magnetoresistance have a hysteretic shape due to the influence of tensile stresses in the (Ga,Mn)As layer grown on top of the relaxed InGaAs material on the appearance of the magnetization component, perpendicular to the structure surface.

Diode p-(GaMn)As/n-InGaAs/n+-GaAs heterostructures with different thicknesses (from 5 to 50 nm) of the (Ga,Mn)As dilute magnetic semiconductor layer have been fabricated and studied. The negative magnetoresistance effect reaching 6–8% is observed in a magnetic field of 3600 Oe; this effect is retained up to temperatures of 70–80 K and related to a decrease in the charge carrier scattering due to ferromagnetic ordering in the (Ga,Mn)As layer. The dependence of the magnetoresistance on the forward bias voltage is nonmonotonic, and the magnetoresistance maximum and the operating voltage rate are dependent on the (Ga,Mn)As layer thickness. The magnetic-field dependence of the magnetoresistance have a hysteresis shape determined by the influence of the tensile stresses in the (Ga,Mn)As layer grown above the relaxed InGaAs on the magnetization component perpendicular to the structure surface.

AbstractA new design for diode heterostructures with (Ga, Mn)As ferromagnetic layers is experimentally investigated. The diode structures are fabricated using a combination of metal-organic chemical vapor deposition (MOCVD) epitaxy and pulsed laser deposition and contain (Ga, Mn)As/ n -InGaAs heterojunctions. The electrical properties of the diodes in a magnetic field applied perpendicular to the p – n junction are examined. The negative magnetoresistance observed at temperatures of <50 K (below the (Ga, Mn)As Curie temperature) is attributed to a decrease in the carrier scattering caused by ferromagnetic ordering and in the potential barrier at the (Ga, Mn)As/ n -InGaAs interface. The observed negative magnetoresistance depends nonmonotonically on the forward bias with a maximum in the voltage region close to the p – n -junction potential barrier height. The maximum can be caused by the decisive contribution of the spin-dependent resistances of the (Ga, Mn)As layer and (Ga, Mn)As/ n -InGaAs interface to the total resistance of the structure. It is found that the dependence of the magnetoresistance on the external magnetic field is hysteretic due to the influence of tensile stresses in the (Ga, Mn)As layer grown on top of a relaxed In_ x Ga_1 –_ x As buffer layer with an indium content of x ≈ 0.1.

Electrically active defects in (Ga,Mn)As/(In,Ga)As/GaAs heteroepitaxial structures, both in GaAs and InGaAs epitaxial layers and near the interface, are investigated by induced current and relaxation spectroscopy. On the images obtained by the induced-current method, extended defects are observed not only near the GaAs–InGaAs interface but also throughout the entire volume of the InGaAs layer, almost to its upper boundary. Two deep levels (at EV of +0.50 and +0.65 eV), which could be related to extended defects, are revealed in the lower part of the band gap in the structures under study. A possible relation between deep levels and extended recombination-active defects detected by the electron-beam-induced current method is discussed.

A new design for diode heterostructures with (Ga, Mn)As ferromagnetic layers is experimentally investigated. The diode structures are fabricated using a combination of metal-organic chemical vapor deposition (MOCVD) epitaxy and pulsed laser deposition and contain (Ga, Mn)As/ n -InGaAs heterojunctions. The electrical properties of the diodes in a magnetic field applied perpendicular to the p – n junction are examined. The negative magnetoresistance observed at temperatures of <50 K (below the (Ga, Mn)As Curie temperature) is attributed to a decrease in the carrier scattering caused by ferromagnetic ordering and in the potential barrier at the (Ga, Mn)As/ n -InGaAs interface. The observed negative magnetoresistance depends nonmonotonically on the forward bias with a maximum in the voltage region close to the p – n -junction potential barrier height. The maximum can be caused by the decisive contribution of the spin-dependent resistances of the (Ga, Mn)As layer and (Ga, Mn)As/ n -InGaAs interface to the total resistance of the structure. It is found that the dependence of the magnetoresistance on the external magnetic field is hysteretic due to the influence of tensile stresses in the (Ga, Mn)As layer grown on top of a relaxed In x Ga 1 – x As buffer layer with an indium content of x ≈ 0.1.

The deep‐level (DL) spectrum of plastically deformed n‐type Si and its modification due to interaction with the mobile Ni species are investigated by the deep‐level transient spectroscopy (DLTS) technique. The used geometry of plastic deformation makes it possible to separate the DL centers associated with the dislocations themselves or with dislocation traces, the quasi‐2D defects left by moving dislocations. It is shown that the chemomechanical polishing at room temperature in a Ni‐contaminated slurry results in the appearance of additional DL centers; the principal part of the novel centers forms due to nickel interaction with the dislocation trails. The DLTS signatures of the nickel‐related defects in our plastically deformed samples are similar to those for the nickel‐silicide precipitates.

The mechanism of cross-hatch (CH) pattern formation on the surface of GaMnAs/InGaAs/GaAs (001) heterostructures with a small lattice mismatch, related to the peculiarities of glide process of dislocations in epilayers, is considered. Electrically active defects in these heterostructures and the surface morphology of epilayers were investigated by electron beam induced current imaging, transmission electron microscopy (TEM), atomic force microscopy and differential interference contrast microscopy in combination with selective chemical etching. The studies revealed a high-density system of extended defects (EDs) in the bulk of InGaAs epilayers in addition to misfit dislocations at the epilayer/substrate interface. These defects possess a number of properties reflecting their unusual core structure: pronounced crystallography, recombination activity, existence of elastic strains in the core, and at the same time the absence of contrast in the TEM images. Model experiments performed on InGaAs epilayers give grounds to consider that the revealed EDs are similar in properties to a new type of EDs generated by moving dislocations in plastically deformed Si and SiGe crystals. The formation of CH surface structure is assumed to be directly related to the emergence of the EDs during the strain relaxation process in heterostructures based on III-V and IV-group materials.

A GaAs/AlAs heterostructure and a GaAs film grown on Si/Ge substrates have been fabricated and studied. A Ge buffer on a silicon substrate was fabricated using the MBE process. A3B5 films were grown by MOCVD at low pressures. Photoluminescence spectroscopy was used to define the optical quality of A3B5 films. Structural properties were investigated using the electron beam induced current method. It was established that despite a rather high density of dislocations on the epitaxial layers, the detected photoluminescence radiation of layers indicates the acceptable crystalline quality of the top GaAs layer.

Metastable hydrogen-related M3/M4 defects in n-GaAs epilayers grown by MOVPE are investigated using the high-resolution Laplace DLTS technique. The clear separation of the M4 peak in two components is experimentally obtained. It is shown that the M4 components have different field dependences of the emission rates and can be resolved in electric fields higher than 4.10(4) V/cm. The relations between the Laplace DLTS signal intensities of M3 defect and that of the M4 components during the metastable transformation of the M3/M4 center are studied and discussed.