Bimetalni Ir-Al Schottkyjevi spojevi na GaAs

We report on novel Ir-Al/GaAs Schottky contact systems based on sequentially evaporated Ir-Al bimetallic multilayers. Electrical and thermal stability of these contact systems are investigated by I- V measurements and Auger depth profiling method. An increase of the barrier height with annealing temperature has been indicated for all Schottky contacts. A model of the barrier height enhancement based on a solid phase epitaxy of a graded AlxGa1-xAs layer at the interface at elevated temperatures was used to explain the electrical and the thermal stability of the contacts. A method of controlling of the barrier height and of the thermal stability of the Ir-Al/n-GaAs interface is proposed.Opisuju se novi Ir-Al/GaAs Schottkyjevi spojevi dobiveni uzastopnim naparavanjem Ir-Al bimetalnih slojeva. Električna i toplinska stabilnost spojeva ispituje se I −V mjerenjima i Augerovim dubinskim profiliranjem. Opaženo je povećanje barijere s povećanjem temperature otpuštanja. Za objašnjenje električne i toplinske stabilnosti spojeva, primijenjen je model povećanja barijere zasnovan na čvrstofaznoj epitaksiji AlxGa1−xAs sloja na granici spoja. Predložen je model upravljanja visinom barijere i toplinske stabilnosti granice Ir-Al/n-GaAs

Bimetalni Ir-Al Schottkyjevi spojevi na GaAs

We report on novel Ir-Al/GaAs Schottky contact systems based on sequentially evaporated Ir-Al bimetallic multilayers. Electrical and thermal stability of these contact systems are investigated by I- V measurements and Auger depth profiling method. An increase of the barrier height with annealing temperature has been indicated for all Schottky contacts. A model of the barrier height enhancement based on a solid phase epitaxy of a graded AlxGa1-xAs layer at the interface at elevated temperatures was used to explain the electrical and the thermal stability of the contacts. A method of controlling of the barrier height and of the thermal stability of the Ir-Al/n-GaAs interface is proposed.Opisuju se novi Ir-Al/GaAs Schottkyjevi spojevi dobiveni uzastopnim naparavanjem Ir-Al bimetalnih slojeva. Električna i toplinska stabilnost spojeva ispituje se I −V mjerenjima i Augerovim dubinskim profiliranjem. Opaženo je povećanje barijere s povećanjem temperature otpuštanja. Za objašnjenje električne i toplinske stabilnosti spojeva, primijenjen je model povećanja barijere zasnovan na čvrstofaznoj epitaksiji AlxGa1−xAs sloja na granici spoja. Predložen je model upravljanja visinom barijere i toplinske stabilnosti granice Ir-Al/n-GaAs

Piezoelektrická analýza saw snímača pomocou metódy konečných prvkov

In this contribution modeling and simulation of surface acoustic waves (SAW) sensor using finite element method will be presented. SAW sensor is made from piezoelectric GaN layer and SiC substrate. Two different analysis types are investigated - modal and transient. Both analyses are only 2D. The goal of modal analysis, is to determine the eigenfrequency of SAW, which is used in following transient analysis. In transient analysis, wave propagation in SAW sensor is investigated. Both analyses were performed using FEM code ANSYS.Príspevok sa zaoberá modelovaním a simuláciou SAW snímača, ktorý využíva šírenie povrchových vĺn, pričom na simulovanie sa využíva metóda konečných prvkov. SAW snímač je zložený z piezoelektrickej GaN vrstvy a z SiC substrátu. Vyšetrované sú dva typy analýz - modálna a prechodová. Cieľom modálnej analýzy je určiť vlastnú frekvenciu SAW snímača, ktorá je následne využitá v prechodovej analýze. V prechodovej analýze sa vyšetruje šírenie sa povrchovej vlny v SAW snímači. Obe analýzy sú realizované v MKP programe ANSYS

Piezoelectric fem analysis of surface acoustic wave sensor

The paper is focused on modeling and simulation of surface acoustic wave devices using finite element method, especially by code ANSYS. SAW sensor is made of piezoelectric GaN layer, in which the Rayleigh waves are generated, and of SiC substrate. Full 3D model of SAW sensor is investigated, where mechanical material model of GaN is considered to be transversally isotropic. Two different analyses are performed: modal and full transient. Modal analysis is performed to determine the speed of the Rayleigh waves in piezoelectric material and also in order to determine the interdigital transducer eigenfrequency, which is used in next transient analysis as electric frequency of excitation. The second analysis is the transient analysis, where the goal is to compare voltage on input and output interdigital transducer as well as wave propagation delay

Femtosecond laser processing of membranes for sensor devices on different bulk materials

We demonstrate that diaphragms for sensor applications can be fabricated by laser ablation in a~variety of substrates such as ceramics, glass, sapphire or SiC. However, ablation can cause pinholes in membranes made of SiC, Si and metals. Our experiments indicate that pinhole defects in the ablated membranes are affected by ripple structures related to the polarization of the laser. From our simulation results on light propagation in Laser-Induced Periodic Surface Structures (LIPSS) we find out that they are acting as a slot waveguide in SiC material. The results further show that field intensity is enhanced inside LIPSS and spreads out at surface distortions promoting the formation of pinholes. The membrane corner area is most vulnerable for pinhole formation. Pinholes funnel laser radiation into the bulk material causing structural damage and stress in the membrane. We show that a~polarization flipping technique inhibits the formation of pin holes caused by LIPSS

Piezoelectric fem analysis of surface acoustic wave sensor

The paper is focused on modeling and simulation of surface acoustic wave devices using finite element method, especially by code ANSYS. SAW sensor is made of piezoelectric GaN layer, in which the Rayleigh waves are generated, and of SiC substrate. Full 3D model of SAW sensor is investigated, where mechanical material model of GaN is considered to be transversally isotropic. Two different analyses are performed: modal and full transient. Modal analysis is performed to determine the speed of the Rayleigh waves in piezoelectric material and also in order to determine the interdigital transducer eigenfrequency, which is used in next transient analysis as electric frequency of excitation. The second analysis is the transient analysis, where the goal is to compare voltage on input and output interdigital transducer as well as wave propagation delay

Piezoelectric Analysis of Saw Sensor Using Finite Element Method

In this contribution modeling and simulation of surface acoustic waves (SAW) sensor using finite element method will be presented. SAW sensor is made from piezoelectric GaN layer and SiC substrate. Two different analysis types are investigated - modal and transient. Both analyses are only 2D. The goal of modal analysis, is to determine the eigenfrequency of SAW, which is used in following transient analysis. In transient analysis, wave propagation in SAW sensor is investigated. Both analyses were performed using FEM code ANSYS