The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
A study of the effect of substrate temperature on oblique-angle sputtered galium-doped zinc oxide (GZO) thin films was carried out. Both the oblique-angle sputtering and the substrate temperature lowered the resistivity of GZO thin films down to 4 × 10-3 Ωcm together with an increase of their optical transmittance over 90%.
Nanocrystalline diamond/amorphous composite carbon films were deposited by plasma enhanced chemical vapour deposition method. The concentrations of species in the films were determined by RBS (Rutherford backscattering spectrometry) and ERD (elastic recoil detection) methods. The RBS results showed the main concentrations of C in the films. The concentration of hydrogen was approximately 20 at.%....
This work presents the properties of nanocrystalline SiC(nc-SiC) films prepared by plasma enhanced chemical vapour deposition. A p-type silicon wafer with resistivity 2-7 Ωcm and (100) orientation was used as the substrate for the nc-SiC:H films. The concentration of species in the SiC films was determined by RBS and ERD. Chemical compositions were analyzed by IR spectroscopy. Film morphology was...
We present results of material optimization for the alignment marks used in the Electron-Beam Direct-Write (EBDW) lithography. Such marks have been proposed both for negative (grooves) as well as for positive (elevated) topographies. The primary mask for the alignment mark patterns is done by photolithography and e-beam lithography. The negative topography of the marks was transferred by Deep Reactive...
In this work, the optimalisation of e-beam parameters and the writing strategy have been performed. Various positive and negative e-beam resists have been evaluated for high resolution e-beam lithography and pattern transfer. Both, lift-off method and ion beam etching have been investigated for the pattern transfer into thin Pt and MoC layer on saphire substrate.
So far the dependence of the spontaneous polarization coefficient for GaN and AlN on temperature has been measured to be minimal, which corresponds with expectation that the spontaneous polarization is reduced at the elevated temperatures of interest. There are also no reports on the piezoelectric polarization at higher temperature. This paper is initial study on the influence of temperature related...
This study is focused on static electrical properties of the InAlN/GaN HFETs with the AlN buffer layer, which have different mechanical strain due to different growth conditions. Investigated devices were tested under off-state high drain bias of 55 V and their performance before and after the stress is analysed. Significant influence of the AlN buffer on the properties of virgin as well as stressed...
GaAs is broadly used in modern electronics. On the other hand, application of GaAs-based devices in high power electronics is complicated due to the substantial excess heat generated during device operation. One possibility to remove the excess heat is to employ substrates with high thermal conductivity. In this contribution we present the growth of GaAs layers by MOVPE on aluminum (111) pseudo-substrates...
Between 5 and 10% of the world's electricity is wasted as dissipated heat in the power electronic circuits needed, for example, in computer power supplies, motor drives or the power inverters of photovoltaic systems. This paper describes how the unique properties of GaN enables a new generation of power transistors has the potential to reduce by at least an order of magnitude the cost, volume and...
This paper reports the capability of AlGaN/GaN HEMTs on Si (111) substrates for microwave power applications above 30 GHz. A current gain cut-off frequency ft=90 GHz and a maximum power gain cut-off frequency fmax=135 GHz are obtained for a 80 nm gate-length transistor. These results, associated with low lag effects, demonstrate the capability of these transistors for high performance, cost effective,...
Recent progress in GaN based high electron mobility transistors (HEMTs) has revealed them to be strong candidates for future high power devices at high frequency operation. In order to extract and utilize the favorable GaN material properties, however, there are still a lot of areas to be investigated. Among them the most important is to develop new processes, structure design and characterization...
Location and properties of traps generated in AlGaN/GaN high electron mobility transistors submitted to electrical stress was studied using an integrated electrical and optical methodology. A spatial and spectral electroluminescence study reveals traps generated during both OFF- and ON-state stress to be located in the gate and access region close to the drain side of the gate edge, while UV-light...
AlGaN/GaN and InAlN/GaN high electron mobility transistors (HEMTs) were fabricated and their electrical and thermal properties were examined. The influence of irradiation to direct current (DC) and low-frequency noise properties of these devices have already been investigated and published. However, the thermal processes in the active layers of these devices can also induce significant changes in...
GaN is a potential sensor material for harsh environments due to its piezoelectric and mechanical properties. In this paper an 8mm diameter sensor structure is proposed based on a GaN/AlGaN/sapphire HEMT wafer. The discs will be glass-bonded to an alumina package, creating a `drumskin' type sensor that is sensitive to pressure changes. The electromechanical behaviour of the sensor is studied in an...
A growing thirst for highly sensitive and sufficiently selective sensors for extremely harsh conditions can be seen. This fact excludes the use of conventional sensing devices and gives a space for Surface Acoustic Wave sensors with monolithically-integrated electronics. We have chosen the AlGaN/GaN material as a suitable material due to its excellent chemical inertness and stability of piezoelectric...
In this paper we report our results of DLTS investigations of deep-level defects in Schottky-gate AlGaN/GaN LP-MOVPE structures grown on sapphire substrate. The exact location of heterostructure's interface below the surface (20 nm) was determined from the concentration profile to depletion region width dependence. The free charge carrier density was calculated (n2D = 4.75÷5.09 × 1016 m-2). Four deep...
In this paper, an atomistic molecular dynamics followed by an electrical simulation study is made to study the turn-on and turn-off characteristics, gain, and breakdown voltage of an optically triggered GaN/4H-SiC hetero-structure vertical NPN device with 1 nm AlN as the buffer layer and the results are compared with the optically triggered all-4H-SiC NPN device. The optically triggered GaN/4H-SiC...
In this paper the results obtained from simulations and measurements on InAlN/GaN HEMTs are presented. The HEMT material structure was modelled by Synopsys TCAD tools and electrical characteristics of the device were simulated by DESSIS. Several effects of the geometry and concentration of interface charges on the electrical characteristics are studied. The interface and surface charges as well as...
The unique electrical and thermal properties of GaN are used to improve two different approaches to generate THz radiation. One method is heterodyne photomixing, where two laser beams with slightly different wavelengths illuminate an ultrafast photodetector. The electrical and mainly the thermal limits of the conventionally used LT-GaAs restrict the THz output power generated by this method up to...
Atomic layer deposition (ALD) technique at 300°C was used to prepare an Al2O3 dielectric layer, to form MOS-HFETs. The static (output and transfer) and dynamic (Capacitance-Voltage) characteristics were used for evaluation of investigated devices. From the static characteristic, an increase of the saturation drain current (up to 35%) and extrinsic transconductance (up to 10%) of the MOS-HFETs were...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.