Jacek Gryglewicz

The selection of gas chemistry in reactive ion etching of AlGaN/GaN heterostructures

In this study, we discuss a scope of different gas mixtures intended for reactive ion etching of AlxGa1¿xN/GaN heterostructures in relation to percentage composition of aluminum. The results of etching process are strongly dependent on the process parameters and gas mixture applied. The selected mixture of BCl3/Cl2/Ar provides a good stability of plasma and quality of etched heterostructure mesas. The test structures of AlGaN/GaN for the RIE process were grown on a c-plane sapphire in a vertical flow LP-MOVPE (low pressure Metalorganic Vapour Phase Epitaxy) system. The surface morphology and topography of mesa structures were studied using atomic force microscope working in tapping mode and scanning electron microscope. The results of etching process for intended process parameters as well as the correlation between the gas mixture, parameters and obtained mesa structures are discussed in this article.

Precise etching of AlGaN/GaN HEMT structures with Cl 2 /BCL 3 /Ar plasma

The aim of work was to develop precise etching process of AlGaN/GaN heterostructures. The study was focused on surface parameters evolution and etch characteristics of etched layers. The surface parameters depended on selection of composition of Cl₂:BCl₃:Ar gas mixture, while the amount of boron trichloride in Cl₂:BCl₃:Ar was crucial in obtaining precise etch rate of thin AlGaN and thick uid-GaN layers. Changing of BCl₃ amount in the Cl₂:BCl₃:Ar mixture in the range of 6% ÷ 60% resulted in increased AlGaN etch rate from 1 nm/min to 19 nm/min and uid-GaN etch rate from 11 nm/min to 55 nm/min. In case of AlGaN almost linear etch characteristic was observed. Surface morphology of uid-GaN was modified by different ratio of BCl₃/Cl₂.

Characterization of Diamond-like Carbon (DLC) films deposited by RF ICP PECVD method

The work presents the results of a research carried out with Plasmalab Plus 100 system, manufactured by Oxford Instruments Company. The system was configured for deposition of diamond-like carbon films by ICP PECVD method. The deposition processes were carried out in CH4 or CH4/H2 atmosphere and the state of the plasma was investigated by the OES method. The RF plasma was capacitively coupled by 13.56 MHz generator with supporting ICP generator (13.56 Mhz). The deposition processes were conducted in constant value of RF generator’s power and resultant value of the DC Bias. The power values of RF generator was set at 70 W and the power values of ICP generator was set at 300 W. In this work we focus on the influence of DLC film’s thickness on optical, electrical and structural properties of the deposited DLC films. The quality of deposited DLC layers was examined by the Raman spectroscopy, AFM microscopy and spectroscopic ellipsometry. In the investigated DLC films the calculated sp3 content was ranging from 60 % to 70 %. The films were characterized by the refractive index ranging from 2.03 to 2.1 and extinction coefficient ranging from 0.09 to 0.12.

Characterization of thin Gd2O3 magnetron sputtered layers

Reactive magnetron sputtering technique using O2/Ar gas mixture was used to deposit Gd2O3 layers. Following metallization process of Al allowed to create MIS structures, which electrical parameters (κ, Dit, UFB, ρ, etc.) were measured using high frequency C-V equipment. Created layers exhibit high permittivity (κ≈12) at 100kHz. I-V measurements point out on maximum electric break down field Ebr≈0.4 MV/cm and maximum break down voltage Ubr ≈ 16V. Layers were morphologically tested using AFM technique (Ra ≈ 0.5÷2nm). Layer thicknesses as well as refractive indexes (RI ≈ 1.50÷2.05) were estimated using ellipsometry measurements.

Characterization of thin Gd2O3magnetron sputtered layers

Reactive magnetron sputtering technique using O2/Ar gas mixture was used to deposit Gd2O3 layers. Following metallization process of Al allowed to create MIS structures, which electrical parameters (κ, Dit, UFB, ρ, etc.) were measured using high frequency C-V equipment. Created layers exhibit high permittivity (κ≈12) at 100kHz. I-V measurements point out on maximum electric break down field Ebr≈0.4 MV/cm and maximum break down voltage Ubr ≈ 16V. Layers were morphologically tested using AFM technique (Ra ≈ 0.5÷2nm). Layer thicknesses as well as refractive indexes (RI ≈ 1.50÷2.05) were estimated using ellipsometry measurements.

Characterization of thin Gd 2 O 3 magnetron sputtered layers

Reactive magnetron sputtering technique using O2/Ar gas mixture was used to deposit Gd2O3 layers. Following metallization process of Al allowed to create MIS structures, which electrical parameters (κ, Dit, UFB, ρ, etc.) were measured using high frequency C-V equipment. Created layers exhibit high permittivity (κ≈12) at 100kHz. I-V measurements point out on maximum electric break down field Ebr≈0.4 MV/cm and maximum break down voltage Ubr ≈ 16V. Layers were morphologically tested using AFM technique (Ra ≈ 0.5÷2nm). Layer thicknesses as well as refractive indexes (RI ≈ 1.50÷2.05) were estimated using ellipsometry measurements.

A silicon photonic quasi-crystal structure obtained by interference lithography

Photonic quasi-crystal structures have been prepared and investigated. Symmetrical patterns were fabricated by interference lithography in negative tone photoresist and transferred to silicon by reactive ion etching. Theoretical influences of pattern detail (radius of hole) on the photonic band gap have been studied. Three types of 2D photonic quasi-crystals have been prepared: 8-fold, 10-fold and 12-fold pattern. Finally, finite-difference time-domain method was used for theoretically prediction of transmission spectrum for fabricated 12-fold quasi-crystal.

Reactive ion etching of Al x Ga 1−x N/GaN heterostructure using Cl 2 , BCl 3 /Ar gas plasma

The etching processes were carried out in Oxford Instruments Plasmalab80Plus system. Present work is concentrating on discussion of a scope of different AlxGa1−xN/GaN heterostructures in relation to percentage composition of aluminum. The topography of heterostructure surface and slope was controlled using AFM technique.