Composition related electrical active defect states of InGaAs and GaAsN

This paper discusses results of electrically active defect states - deep energy level analysis in InGaAs and GaAsN undoped semiconductor structures grown for solar cell applications. Main attention is focused on composition and growth condition dependent impurities and the investigation of their possible origins. For this purpose a widely utilized spectroscopy method, Deep Level Transient Fourier Spectroscopy, was utilized. The most significant responses of each sample labelled as InG2, InG3 and NG1, NG2 were discussed in detail and confirmed by simulations and literature data. The presence of a possible dual conduction type and dual state defect complex, dependent on the In/N composition, is reported. Beneficial characteristics of specific indium and nitrogen concentrations capable of eliminating or reducing certain point defects and dislocations are stated

Potentiostatic Electrodeposition of Cu2O under Light and Dark for Photoelectrochemical Hydrogen Generation Applications

Potentiostatic electrodeposition conducted at various deposition voltages from lactate-stabilized copper sulfate electrolyte was used for preparation of Cu2O layers for Photoelectrochemical (PEC) production of hydrogen. A novel approach based on an application of light during the electrodeposition is utilized to suppress the potential drop in the Cu2O layer during the potentiostatic deposition. Structures prepared under dark and light on an Ag substrate are analyzed by X-Ray Diffraction analysis (XRD), Scanning Electron Microscopy (SEM) and Linear Sweep Voltammetry (LSV). It was shown that the application of light increases the deposition rate due to the contribution of the photogenerated carriers. The deposition voltage affects the photoresponse of light deposited structures but causes only a negligible change in dark deposited structures. The light deposited samples exhibited a higher photoresponse for all deposition voltages. The presented study suggests the light potentiostatic electrodeposition as an attractive approach for the preparation of Cu2O structures for cheap and efficient photoelectrochemical water splitting applications

Dielectric Properties and Breakdown of the Gate Oxide in the MOS Structure

The article treats the methodology of measuring the breakdown voltage on Si-based MOS structures. Identification of defects in the thin gate oxide is performed using the Weibull statistical analysis. By comparing the current and capacitance measurements on MOS structures we determined the influence of the defect charge in the oxide upon the parameters characterizing the breakdown. A higher occurrence of defects was correlated with elevated values of the flat band voltages. This verifies the hypothesis of an increased destruction of MOS structures caused by electrically active defects arising in the course of thermic oxidation and pre-oxidation treatment of the surface of silicon

Radiation Hardness of Mos Structures Exposed to High-Energy Ions

MOS structures exposed to 305 MeV Kr and 710 MeV Bi ions irradiation with fluences of 109 cm2 and 1010 cm2 were investigated by capacitance measuring methods (C-V, C-t), completed by quasistatic low-frequency C-V and DLTS measurements.The irradiated MOS structures were functional in spite of a high density of radiation defects. The electric activity of the defects brought a sharp decrease in the generation parameters tr and g. The parameters of six deep levels were detected in the MOS structures exposed to 710 MeV Bi ions irradiation. Five of these levels with energies 0.52 eV, 0.14 eV, 0.17 eV, 0.25 eV, 0.27 eV were radiation defects

Characterization of Unipolar Power Devices Technology

The quality of momentus technological steps in unipolar power devices manufactoring was examine by means of capacitance and current measurements using a metal-oxide-semiconductor capacitors (MOS-C). From the low- (If) and high-frequency (hf) capacitance-voltage (C-V) curves, the effective defect charge and energy distribution of Si-SiO2 interface trap density were extracted, respectively. performin non-steady capacitance-time (C-t) and the time domain constant-capacitance (cC-t) at well as deep level transient spectroscopy (DLTS) techniques we have analysed electrically active that generation parameters are mostly influenced by traps at the Si-SiO2 interface. Moreover, breakdown voltage measurement confirms high quality and homogeneity of thermal oxide. Low density of carrier traps was achieved by intrinsic gettering technique

Characterization of High Energy Irradiated MOS Structures Using the Capacitance Methods

The formation and annealing of radiation-induced defects in MOS structures exposed to 710 MeV Bi ions and 305 MeV Kr ions radiation with a fluency of 10^9 and 10^10cm^2 have been studied by capacitance methods. Electrical activity of the defects has braought increase of interface trap density Dit and a sharp decrease in the generation parameters tr and τg. The parameters of nine deep levels were detected in the investigation MOS structures. Eight of these levels were radiation defects.<br /

Application of Open Circuit Voltage Decay to the Characterization of p/n+ and n/p+ Epitaxial Layer

High quality silicon epitaxial layers are inevitable in bipolar and/or unipolar technology. However, its properties are not as easy characterized as those of bulk material. The recombination lifetime is dominated by surface/interface recombination for thin layers, which epitaxial ones generally are. We have designed diode structure with n+n/p+and  p+p/n+ epitaxial layer for open circuit voltage decay (OCVD) technigue. In such a structure, injected carriers are constrained within lightly doped base by potential barriers of junction and high-low contact and their concentration can then decrease only by recombination. Carrier lifetime obtained by this manner yields information mainly about the defect properties of epitaxial layer. Performing OCVD measurement for high-level injection condition, also tn and tp could be evaluated

Charge injection and transport properties of an organic light-emitting diode

The charge behavior of organic light emitting diode (OLED) is investigated by steady-state current–voltage technique and impedance spectroscopy at various temperatures to obtain activation energies of charge injection and transport processes. Good agreement of activation energies obtained by steady-state and frequency-domain was used to analyze their contributions to the charge injection and transport. We concluded that charge is injected into the OLED device mostly through the interfacial states at low voltage region, whereas the thermionic injection dominates in the high voltage region. This comparison of experimental techniques demonstrates their capabilities of identification of major bottleneck of charge injection and transport