One of the major limitations of oxide semiconductors technology is the lack of proper p-type materials to enable devices such as pn junctions, light-emitting diodes, and photodetectors. This limitation has resulted in an increased research focus on these materials. In this work, p-type NiOx thin films with tunable optical and electrical properties as well as its dependence with oxygen pressure during pulsed laser deposition are demonstrated. The control of NiOx films resistivity ranged from ∼109 to ∼102 Ω cm, showing a p-type behavior with Eg tuning from 3.4 to 3.9 eV. Chemical composition and the resulting band diagrams are also discussed. The all-oxide NiOx–Ga2O3 pn junction showed very low leakage current, an ideality factor of ∼2, 105 on/off ratio, and 0.6 V built-in potential. Its J–V temperature dependence is also analyzed. C–V measurements demonstrate diodes with a carrier concentration of 1015 cm–3 for the Ga2O3 layer, which is fully depleted. These results show a stable, promising diode, attracti...

Tunable Electrical and Optical Properties of Nickel Oxide (NiOx) Thin Films for Fully Transparent NiOx–Ga2O3 p–n Junction Diodes

This paper presents SMD components assembly by non-conductive adhesives. Two types of non-conductive adhesives were used for the experiment - UV curable acrylic adhesive Loctite AA3926 and two-part epoxy adhesive Loctite HY4092 GY. The purpose of the experiment was to achieve good mechanical and electrical properties of the joint between the SMD component and copper pads made on flexible DuPont Kapton foil. The electrical conductivity was achieved only by mechanical contact of the component and substrate pads. Therefore, the mechanical pressure on the component during curing was important just as the adhesive's shrinkage rates. Also, the adhesive's amount causes a noticeable joint property modification. The assembly of the SMD components by non-conductive adhesives was comparable with quite commonly used conductive adhesives within the electrical and shear strength mechanical properties.

SMD Components Assembly on a Flexible Substrate by Non-Conductive Adhesives

Detailed investigation of Ohmic Cr/Ni/Au based contact formation to p-GaN was realized by scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy and compared to the Cr/Au bilayer metallization scheme. The authors found that it is essential to introduce a nickel film in Cr-based contacts and anneal the trilayer structure in air in order to suppress the Shottky barrier and thus obtain the Ohmic contact. Our findings also indicate that oxygen behaves as a dopant dispersed in chromium nitride matrix. Thus Ohmic trilayer Cr/Ni/Au contact to p-GaN annealed in air is formed by Ni–Ga–Au alloy mixed with Au–Ga-doped Cr2N crystalline composites. Possible ways for improvement of such types of contact are discussed.

Mechanism of Ohmic Cr/Ni/Au contact formation on p-GaN

The influence of an ultrathin Ni interface layer on the performance of GaN-based 380 nm UV LED with sputtered Zn 1−x Mg x O: Al transparent p-type electrode

Abstract This article deals with the impact of electrically conductive adhesive quantity on the shear strength of joints glued by adhesives “EPO-TEKⓇ H20S” and “MG8331S” on three types of substrates (FR-4, MELINEXⓇST504, DuPont™ PyraluxⓇAC). These joints were made by gluing chip resistors 1206, 0805 and 0603, with two curing profiles for each adhesive. Different thicknesses of stencil and reductions in the size of the hole in stencils were used for this experiment. These differences have an effect on the quantity of conductive adhesives which must be used on the samples. Samples were measured after the curing process by using a shear strength test applied by the device LabTest 3.030. This article presents the effects of different curing profiles, various types of substrates, and different quantities of adhesives on the mechanical strength of the joint.

/pdf/shear-strength-of-conductive-adhesive-joints-on-rigid-and-2yxbv83dl2.pdf

Shear Strength of Conductive Adhesive Joints on Rigid and Flexible Substrates Depending on Adhesive Quantity

The paper presents the measured depth distribution of elements and of their chemical states in a Ni/C multilayered structure prepared by pulse laser deposition (PLD), the thicknesses of respective layers being dC = 1.7 nm and dNi = 2.1 nm. By simulating the sputtering process and applying factor analysis to the measured Auger depth profiles we have found that the measured depth distribution is notably affected by the process of sputtering (mainly by atomic mixing and preferential sputtering), and that nickel and most likely also carbon are contained in the multistructure in two basic chemical states, namely as pure elements and as a carbide.

/pdf/quantitative-auger-depth-profiling-of-ni-c-multilayers-by-qy7aftukjo.pdf

QUANTITATIVE AUGER DEPTH PROFILING OF Ni/C MULTILAYERS BY FACTOR ANALYSIS AND COMPARISON WITH T{DYN SIMULATIONS

We have studied the electrical properties and depth concentration profiles of Au/Ni-Zn-O/p-GaN and Au/Ni-Zn/p-GaN, thus of structures containing zinc as a p-type dopant utilized to increase the concentration of free charge carriers in the subsurface region of GaN and to gain a low-resistance ohmic contact. The layers were deposited on p-GaN by DC reactive magnetron sputtering. The prepared contact structures were annealed in N2 , structure Au/Ni-Zn/p-GaN also in O2 . The contact structures containing zinc exhibited lower values of contact resistivity in comparison with those without zinc. It was also found that the values of contact resistivity for both Au/Ni-Zn-O=p-GaN and Au/Ni-Zn/p-GaN were the same, thus it was not affected by the presence of a small content of oxygen (< 0:2 at%) in the working atmosphere during the deposition of layers. Similarly, various gaseous ambients ( N2 or a mixture of N2 + O2 ) during subsequent annealing of the contacts had no observable influence upon the magnitude of the contact resistivity. In our opinion the ohmic nature of the Au/Ni-Zn-O/pGaN and Au/Ni-Zn/p-GaN contacts is related to a reconstruction of the contacts to a sequence metal/p-NiO/p-GaN due to annealing in nitrogen or in a mixture of oxygen and nitrogen and the ohmic properties of the contacts are predetermined by creating a thin NiO oxide layer on the metal/p-GaN interface. We believe that the lower values of the contact resistance in Au/Ni-Zn-O/p-GaN and Au/Ni-Zn/p-GaN contacts than in structure Au/Ni-O/p-GaN are caused by an enhanced hole concentration in the surface region of p-GaN due to zinc diffusion from the zinc-doped contact layer. K e y w o r d s: p-GaN, Au/Ni-Zn-O/p-GaN contact structure, AES depth profiling, low resistance ohmic contact

/pdf/communications-ohmic-contacts-to-p-gan-using-au-ni-zn-o-1mgxciywbu.pdf

COMMUNICATIONS OHMIC CONTACTS TO p{GaN USING Au/Ni{Zn{O METALLIZATION

Nickel oxide (NiO) thin films were deposited on unheated Si substrates by reactive d.c. magnetron sputtering. A pure metallic nickel target was sputtered in a mixture of argon and oxygen. The oxygen content in the gas mixture was changed in the range from 20 to 44 %. After deposition the prepared NiO films were annealed at 500 C for 8 hours in dry air. The films were characterized by X-ray diffraction (XRD), Auger electron spectroscopy (AES), and atomic force microscopy (AFM). Only as-deposited films in the metal-sputtering mode are crystalline. Annealing in dry air gives rise to crystalline phases in all samples. All examined NiO films were semiconductors and their conductance increased by four orders of magnitude between 25 and 350 C.

/pdf/properties-of-sputtered-nio-thin-films-3s9n3a34gk.pdf

Peter Vogrin

Papers

QUANTITATIVE AUGER DEPTH PROFILING OF Ni/C MULTILAYERS BY FACTOR ANALYSIS AND COMPARISON WITH T{DYN SIMULATIONS

COMMUNICATIONS OHMIC CONTACTS TO p{GaN USING Au/Ni{Zn{O METALLIZATION

PROPERTIES OF SPUTTERED NiO THIN FILMS