The growth, structure, and annealing behavior of Al films, formed by in situ vapor deposition on GaN(0001)–(1×1) near 25 °C, have been studied using Auger, electron energy loss, x ray and ultraviolet photoemission spectroscopies and low‐energy electron diffraction. Film growth occurs by a Stranski–Krastanov process with reaction at the immediate interface leading to metallic Ga. Annealing at ≳800 °C leads to release of N, which reacts with Al to form a (1×1)‐ordered layer of AlN, possibly alloyed with a small amount of Ga. The AlN layer has been characterized using the various spectroscopies, and the work function, band bending, and electron affinity of GaN and of the AlN overlayer have been obtained. The Al/GaN Schottky barrier height has been measured and compared with previous results for Ni/GaN.

The growth and properties of Al and AlN films on GaN(0001)–(1×1)

Aluminum alloys AlMgSi1 and AlSi7 have been implanted with nitrogen ions by means of the plasma immmersion ion implantation technique. The samples have been characterized by X-ray photoelectron spectroscopy. Al 2p and N 1s signals could be separated into sub-peaks, corresponding to differently bound states, dependent on the depth below the sample surface and the oxygen concentration. AlN was formed in all implanted samples. An enhancement of the oxygen signal arose in the range between the AlN and metallic aluminum signals. The alloying elements magnesium and silicon showed a strong radiation-enhanced effect of segregation.

XPS investigation of AlN formation in aluminum alloys using plasma source ion implantation

To advance the understanding of fundamental physical and chemical processes occurring in ion bombardment of metals, ion beam nitridation of aluminium, iron, copper and gold is studied in the energy range 2-5 keV, at current densities of 1 and 5 μA cm -2 , for each ion energy. The concentration profiles of nitrogen-ion-implanted metals were measured by x-ray photoelectron spectroscopy (XPS). The chemical composition and chemical structure of the implanted metals were also investigated.

Study of low energy high dose nitrogen implantation in aluminium, iron, copper and gold

A thin nitride layer containing high amounts of oxygen is formed on the surface of A1995 treated by Plasma Immersion Ion Implantation (PIII) at temperatures up to 500°C Below this layer, nitrogen is found in a diffusion zone several microns thick but does not form nitrides The thickness of the diffusion zone is dependent on the treatment temperature Microhardness measurements reveal a decrease in hardness due to a loss of work-hardening In spite of this annealing, both the wear and corrosion resistance are improved

Plasma immersion ion implantation of pure aluminium at elevated temperatures

Aluminum nitride films were synthesized by electron gun (e‐gun) evaporation of aluminum onto Si(111) wafer and glassy carbon, with simultaneous bombardment by 5–20 keV nitrogen ions. Under specific experimental conditions, polycrystalline AlN films of fine crystallinity were obtained by this method. The correlation between experimental parameters and the resulted structure as well as the stoichiometry of the AlN films is also discussed.

Polycrystalline AlN films of fine crystallinity prepared by ion‐beam assisted deposition

Aluminium has been implanted with nitrogen ions at different temperatures. The implanted samples have been characterized by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and electron energy-loss spectroscopy (EELS). Deconvolution procedures are needed to separate the influence of the ion sputter profiling by AES and XPS from the nitrogen-ion-beam-induced effects. The chemical state of Al, N, O and C was identified by deconvolution of the measured spectra. In general, there were double-peak structures observed for N 1s and O 1s, identified as contributions from nitrides and weakly bound nitrogen, and oxides and weakly bound oxygen, respectively. Auger analysis confirms the influence of the nitrogen ion fluence on the shape of the concentration distribution. The influence of temperature on the chemical state of implanted aluminium and on the concentration distribution is discussed.

G. Leonhardt

Papers

Characterization of nitrogen-ion-implanted aluminium