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Pd/GaN(0001) interface properties

Grodzicki M., Mazur P, Zuber S., Pers J, Ciszewski A.

Materials Science Poland

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2014

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Vol. 32, No. 2

252--256

EN

Institute of Experimental Physics, University of Wroclaw, pl. Maxa Borna 9, 50-204 Wrocław, Poland This report concerns the properties of an interface formed between Pd films deposited onto the surface of (0001)-oriented n-type GaN at room temperature (RT) under ultrahigh vacuum. The surface of clean substrate and the stages of Pd-film growth were characterized in situ by X-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), ultraviolet photoelectron spectroscopy (UPS), and low energy electron diffraction (LEED). As-deposited Pd films are grainy, cover the substrate surface uniformly and reproduce its topography. Electron affinity of the clean n-GaN surface amounts to 3.1 eV. The work function of the Pd-film is equal to 5.3 eV. No chemical interaction has been found at the Pd/GaN interface formed at RT. The Schottky barrier height of the Pd/GaN contact is equal to 1.60 eV.

2

TiO2 thin films grown on SiO2–Si(111) by the reactive evaporation method

Grodzicki M, Wasielewski R, Mazur P, Zuber S, Ciszewski A

Optica Applicata

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2013

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Vol. 43, nr 1

99--107

EN

TiO2 thin films were grown on silicon substrates using an electron-beam evaporator. Grainy TiO was used as the evaporation material. Temperature substrate during TiO2 growth was relatively low (about 150 °C), what is important for many optoelectronic devices and multilayers mirrors. High vacuum condition allows to maintain clean surfaces substrates before and during oxide growth. The morphology of titanium oxide thin films was ex situ investigated using atomic force microscopy operating in contact mode, X-ray photoelectron spectroscopy, X-ray powder diffractometry, and by means of a contact angle analyzer. The influence of annealing treatment and exposure to UV–VIS radiation on the morphology has been also discussed.

3

Cr ohmic contact on an Ar+ ion modified 6H-SiC(0001) surface

Grodzicki M., Chrzanowski J., Mazur P., Zuber S., Ciszewski A.

Optica Applicata

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2009

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Vol. 39, nr 4

765-772

EN

Chromium layers were vapor deposited under ultrahigh vacuum onto samples cut out of a single crystal of 6H-SiC(0001) that were Ar+ bombardment modified. The substrates and electrical contacts formed by the Cr adlayer were characterized in situ by current-sensing atomic force microscopy (CS-AFM) and X-ray photoelectron spectroscopy (XPS). Cr/SiC contacts reveal a good I-V characteristic linearity without the use of heavy impurity doping and high-temperature annealing.

4

Effects of Ar+ ion sputtering on morphology and electric conductance of 6H-SiC (0001) surface

Mazur P., Zuber S., Grodzicki M., Ciszewski A.

Materials Science Poland

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2008

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Vol. 26, No. 2

265--269

EN

The paper reports surface modification of SiC by Ar+ ion sputtering. Observations were performed with an ultra high vacuum atomic force microscope operating in the contact mode. The surface morphology and topography were investigated with simultaneous measurement of local changes in electric conductance. We show that the Ar+ ion bombardment of the 6H-SiC wafer surface affects the surface stoichiometry, changing the character of a metal/SiC contact from the Schottky barrier diode type into an ohmic contact type.